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STEM activity of the week – Fun for all ages!

Week 33 – How to Make Invisible Ink

This low-tech invisible ink science experiment lets kids send secret messages to friends and family. All they’ll need is a little lemon juice or milk. We decided to try both versions of this invisible ink experiment to see if the results were any different.

What you need

  • a piece of paper
  • a cotton swab
  • a heat source (a lamp or electric stove works)
  • milk or lemon (or try both)

What to do

  1. Gather your ingredients and tools
  2. If you are using lemon juice, squeeze your lemon into a glass. You can mix it with a little bit of water. Dip your cotton swab into the milk or lemon juice and start writing your message. Let your message dry completely.
  3. Apply heat to get the secret message to appear.  Once dry, an adult should hold the sheet of paper over a heat source. We used an electric stovetop. You can also use a lamplight or blow-dryer.
  4. As the milk or lemon “ink” heats up, it will oxidize and turn brown. You can try this experiment with other substances such as vinegar, honey, or orange juice.    Your messages will appear like magic! 

Cloud in a Jar!

What you need:

  • glass jar with lid or a glass cup with a small plate
  • matches or hairspray
  • hot water
  • ice

Making the Cloud

This demo couldn’t be easier and really could be done by your kiddo from start to finish.  

  1. To get started, we added a couple inches of warm-hot water to our jar. 
  2. Next, we took the lid to the jar, turned it upside down, and filled it with ice.
  3. The final step was to add condensation nuclei or a seed- some tiny particles of dust, salt, pollution, or smoke that the water vapor can condense on in the air.  We used the smoke from matches as our seed but for a kid-friendly version, you could  use a spritz of aerosol hairspray instead.
  4. We found it worked best to blow the match out inside the jar so most of the smoke would become trapped inside. So I lit the match, placed it inside the jar and blew out the match before he quickly placed the lid with ice on top of the jar.  (If you are using a glass cup, use a plate with ice to cover your cup.)
  5. You can see at first the glass is clear because no condensation has formed yet.  Within seconds, however, faint swirls of cloud form.
  6. After a minute or two comes the best part of the whole process: letting out the cloud.

The Science Behind It

For clouds to form they need 3 things; water, cool air, and condensation nuclei. 
Water vapor evaporates from the surface water.  As it rises, the air cools.  The cooler air higher in the atmosphere cannot hold as much water vapor as the warmer air near the surface of the earth.
Some of the water vapor wants to condense, but in order to change from a gas to a liquid, water needs a non-gaseous surface.  Cloud condensation nuclei (CCN) or cloud seeds provide that surface.  CCN’s can be any tiny solid or liquid found in the atmosphere, usually salt from the ocean, dust, or pollution.
In this demonstration you added water vapor to the jar by using warm water.  The smoke or hairspray acted as the cloud seed.  When you added the ice filled lid on top you cooled the warm air causing it to condense on the surface of the cloud seed particles, forming a cloud!


Week 29 – Make an Alka-Seltzer Powered Lava Lamp

Have you ever seen a lava lamp? They were the height of 1960’s “groovy” room decorations. A few minutes after turning it on, a lava lamp has blobs of colored liquid floating towards the top of the lamp and then drifting back down. Making an actual lava lamp that you plug in would require some effort and unusual supplies, but you can create a non-electric version in just a few minutes with the help of the fizzing power of Alka-Seltzer. In this activity you can find out how to make your own…

What you need:

  • Tall identical jars or bottles, such as empty, clear, plastic 1-liter or 2-liter bottles (2)
  • Knife
  • Cutting board
  • Timer or clock that shows seconds
  • Water
  • Food coloring
  • Vegetable oil (enough to fill the jars nearly full)
  • An Alka-Seltzer tablet. Only one tablet is needed for the activity, but having additional tablets can be fun if you wanted to repeat lava lamp action.
  • A way to make one jar hot and one cold, such as by using a large bowl filled with hot water and access to a refrigerator or freezer

What to do:

  1. For each jar or bottle, fill it with 1-2 inches of water, add 5 drops of food coloring, and then fill it at least three-quarters full with vegetable oil. Put the cap on tightly to avoid spills and leaks.$item.AltText
  2. Make one of the prepared jars hot and one cold. For example, to make one hot you could let it sit in a large bowl of hot water, and to make one cold you could store it in a refrigerator or freezer. Be careful when handling hot water.
  3. While you are heating and cooling the jars, cut an Alka-Seltzer tablet into quarters. Only two quarter pieces are needed for the activity, but having additional pieces can be fun if you wanted to repeat lava lamp action.$item.AltText
  4. Once one jar is hot and one is cold, get a timer or clock ready and drop a quarter of a tablet into the heated jar. Note that the tablet piece may take a moment to sink through the vegetable oil to reach the water, where it will react. Start timing as soon as the tablet piece reaches the water and starts reacting.
    How long does it take the tablet to disappear? How vigorous are the bubbles?
  5. Now drop a quarter of a tablet in the cold jar. Time how long it takes the tablet to disappear this time.
    How long does it take the tablet to disappear in the colder liquid?
  6. Think about how the two reactions looked. Do you notice other differences in how the reaction happens in the colder liquid versus in the hotter liquid? Why do you think you got the results that you did?

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Week 28 – Make a Cotton Ball Launcher

What you need

  • Short pencil or popsicle stick
  • Thin rubber bands (2)
  • Cardboard tube (2 empty toilet paper tubes or empty paper towel tube cut in half)
  • Packing tape or other strong tape
  • Scissors
  • Cotton balls
  • Single hole punch

Procedure

  1. Use your scissors to cut one of the toilet paper tubes in half lengthwise.
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  2. Squeeze the roll so that it becomes narrower, about half the original diameter, then tape it to hold in place.
  3. Use your scissors or your hole punch to punch two holes in the skinny tube (if you are using a popsicle stick, use scissors to make narrower holes the same shape as the popsicle stick). Make the holes opposite one another, half an inch away from the end, so that you can poke your pencil or popsicle stick all the way through the tube.
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  4. Carefully push your pencil or popsicle stick through the holes.
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  5. On your second toilet paper tube, cut two slits into one end of the tube, about 1/4 inch long and 1/2; inch apart.
  6. Cut two more slits on the same end of the tube, directly across from the first two.
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  7. Carefully loop one rubber band through the slits on one side, so that it hangs from the cardboard piece in the middle. Put a piece of tape over the slits to reinforce the cardboard tab.
  8. Loop the other rubber band through the slits on the other side of the tube. When you are finished, the tube should have a rubber band hanging from each side.
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  9. Holding the rubber band tube so that the rubber bands are at the top, slide the narrower tube into the wider one, with the pencil end at the bottom.
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  10. Carefully loop each rubber band end around the pencil.
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  11. Hold your launcher so that the pencil is at the bottom. Place a cotton ball on the top, so that it rests inside the narrower tube.
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  12. Hold your launcher slightly horizontally without dropping the cotton ball.
  13. Pull back on the pencil so that the inner tube extends two inches out the back of the launcher. Carefully aim your cotton ball—away from people!
  14. Release the pencil and watch your cotton ball fly!

What Happened?

In this activity, you used two types of energy to load and launch your cotton ball. As you drew back on the pencil with the cotton ball loaded, you added potential energy to the system. The farther you pulled back on the pencil, the more potential energy was being stored. When you released the pencil, the potential energy became kinetic energy, and the cotton ball should have gone flying through the air!

As you pulled back farther on your launcher, more potential energy was added to the system. And the more potential energy you stored, the more kinetic energy should have been released when you shot the cotton ball. As a result, the farther you pulled back on the launcher, the farther the cotton ball should have traveled.


Week 27 – Homemade Bath Fizzies

What you need: 

  • 1 cup baking soda
  • ½ cup citric acid
  • ½ cup Epson salt
  • ½ cup corn starch
  • ¾ tsp water
  • 2 tsp essential oil
  • 1 tsp coconut oil (melted to make liquid)
  • A few drops of soap colorant

What to do: 

  1. Combine all of your dry ingredients into a large bowl and stir together with a whisk.
  2. Place all of your wet ingredients in a small bowl and stir until they are well mixed.
  3. Slowly pour the wet ingredients into the dry ingredients and stir. (They should start to clump in your hand.)
  4. Pack the mixture into your molds as tightly as you can.
  5. After a few minutes, carefully remove your bath fizzies from your molds and place them on wax paper.
  6. Allow them to dry at least a day before using.
  7. Store in an airtight container.

Week 25 – Climate Challenge! Test your knowledge!

Columbia University and the National Oceangraphic and Atmospheric Administration (NOAA) invite you to our climate challenge. Join us in exploring the social, economic, and environmental aspects of climate change!

https://kahoot.com/academy/study/collections/climate-challenge/


Week 24 – How to build a simple balance scale out from a hanger (Great for pre-schoolers)

What you need:

  • plastic hanger
  • two paper or plastic cups
  • string/yarn
  • hole punch.

What to do:

  1. At the top of each cup punch two holes on opposite sides and string yarn through.
  2. Hang the cups on the hangar and place different items in the cup to see which one is heavier.

There are a lot of variations online to expand on the learning. You can compare objects by size, or quantity, or you can ask questions like, “how many Legos does this toy car weigh?”, finding how many Legos it takes to balance a scale with a toy on the other end. This has so much opportunity for learning number comparisons, counting, and thinking skills.


Week 23 – Make Ice Cream in a Bag!

You will need: 

  • Measuring spoons
  • Measuring cup
  • Sugar
  • Half-and-half. Alternatively, milk or heavy whipping cream
  • Vanilla extract
  • Salt. Different types of salts, such as table salt or rock salt, will all work, but may give slightly different results.
  • Ice cubes (8 C)
  • Small, sealable bags, such as pint-sized or sandwich-sized Ziplocs (2)
  • Gallon-sized sealable bags (2)
  • Oven mitts or a small towel
  • Timer or clock

What to do:

  1. In each small sealable bag, place one tablespoon of sugar, ½ cup of half-and-half (or milk or heavy whipping cream), and ¼ teaspoon of vanilla extract. Seal both bags well.
  2. Add four cups of ice cubes to one of the large, gallon-sized bags. Then add ½ cup of salt to the bag.
    Think about: What do you think the salt will do?
  3. Put one of the small bags you prepared into the large bag with the ice cubes. Be sure both bags are sealed shut.
  4. Put on oven mitts or wrap the bag in a small towel and then shake the bag for five minutes. Feel the smaller bag every couple of minutes while you shake it, and take a peek at it.
    Think about: What happens to the ingredients over time? When five minutes are up, how do the ingredients look? What about the ice cubes — how do they change over time, and how do they look by the end?
  5. Now add four cups of ice cubes to the other large, gallon-sized bag, but this time do not add any salt to it. What do you think will happen without using salt?
  6. Put the other small bag you prepared into this large bag. Be sure both bags are sealed.
  7. Put on oven mitts or wrap the bag in a small towel and then shake the bag for five minutes, as you did before. Again, feel the smaller bag every couple of minutes while you shake it, and take a peek at it.
    Think about:
    What happens to the ingredients over time now? When five minutes are up, how do they look now compared to last time? What about the ice cubes — did they change in the same way?
  8. You can also compare how cold the different ice cube bags feel. Does one feel much colder than the other?
  9. If you successfully made some ice cream, you can enjoy it now as a tasty reward for your chemistry challenge! If one of your bags did not make ice cream, check out the Further Exploration section for tips on turning it into ice cream.

What Happened?

You should have seen that the ice cubes in the large bag with salt melted much more, and felt much colder, than the ice cubes in the large bag without salt. Because it was cold enough (several degrees below freezing), the ice cube bag with salt should have been able to cool the ingredients enough to harden them and turn them into ice cream. In contrast the ice cube bag without salt was not cold enough to do this and the ingredients should have remained fluid.

Do not worry, the second bag is not wasted! — you can go back and turn the still liquid ingredients into ice cream! Simply put the small bag in the large bag that had ice cubes and salt and shake them for another five minutes.

If you have ever made ice cream with an old-fashioned hand-crank machine, you probably packed a mixture of ice and rock salt around the container holding the cream. The salt allows the ice and salt mixture to get colder than pure water ice. This extra-cold mixture of salt and ice is able to freeze the ingredients in the ice cream machine (and in the bags you used in this activity) and turn them into ice cream. (This is the same process that goes on when icy roads have salt spread on them to melt the ice.) While pure water freezes at 0 degrees Celsius (32 degrees Fahrenheit), water mixed with salt will freeze below 0 degrees Celsius.


Week 22 – The Incredible Hoop Glider!

You will need:

  • A regular plastic drinking straw
  • 3 X 5 inch index card or stiff paper
  • Tape
  • Scissors

What to do:

  1. Cut the index card or stiff paper into 3 separate pieces that measure 1 inch (2.5 cm) by 5 inches (13 cm.)
  2. Take 2 of the pieces of paper and tape them together into a hoop as shown. Be sure to overlap the pieces about half an inch (1 cm) so that they keep a nice round shape once taped.
  3. Use the last strip of paper to make a smaller hoop, overlapping the edges a bit like before.
  4. Tape the paper loops to the ends of the straw as shown below. (notice that the straw is lined up on the inside of the loops)
  5. That’s it! Now hold the straw in the middle with the hoops on top and throw it in the air similar to how you might throw a dart angled slightly up. With some practice you can get it to go farther than many paper airplanes.

How does it work?

Can we really call that a plane? It may look weird, but you will discover it flies surprisingly well. The two sizes of hoops help to keep the straw balanced as it flies. The big hoop creates “drag” (or air resistance) which helps keep the straw level while the smaller hoop in at the front keeps your super hooper from turning off course. Some have asked why the plane does not turn over since the hoops are heavier than the straw. Since objects of different weight generally fall at the same speed, the hoop will keep its “upright” position. Let us know how far you were able to get the hoop glider to fly. Tell us on the Science Bob Facebook Page.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does the placement of the hoops on the straw affect its flight distance?
2. Does the length of straw affect the flight? (You can cut the straws or attach straws together to test this)
3. Do more hoops help the hoop glider to fly better?
4. Do the hoops have to be lined up in order for the plane to fly well?


Week 21 –  Make a T-Shirt Tote

This clever upcycle project will fit you and your kids to a tee! Cleaning out your closet? Don’t ditch that old freebie or concert t-shirt – give it new life as a cool tote bag. This is great way to clear out the clutter, make room for new clothes and teach your kids about upcycling.  

What you’ll need:

  • Cotton T-shirt (Don’t have a t-shirt? No problem! Use a pillow case!)
  • Scissors
  • Pen

Follow these steps:

  1. Lay the T-shirt on a flat surface and outline the cut-out for the neck line.
  2. Cut off the neck. Cut through both layers of fabric at the same time.
  3. Cut off the sleeves. Remember to cut through both layers of fabric at the same time.
  4. Cut 1-inch-wide, 4-inch-long strips of fringe into the bottom of the T-shirt, or long enough for you to tie 4 double knots. Cut through both layers of fabric at the same time.
  5. If there is a graphic or logo on the T-shirt that you want visible on the bag, turn the shirt inside-out at this point. If you want to hide a logo, leave the shirt right-side-out.
  6. Flip up one layer of the fringe so you can see the corresponding pair below.
  7. Starting at the edge, tie 2 over-hand knots in the fringe. Pull tight so the fabric stretches a bit. Continue for all of the fringe pairs.
  8. Starting at the edge again, tie the two adjacent knots together by tying another double knot using the fringe pair to the left and one strip of the fringe pair to the right. Remember to pull tight.
    Now turn the T-shirt inside — out and your tote is ready to use!

TRY THIS:

Don’t have a cotton T-shirt or pillow? Try a T-shirt made of a different fabric, or another tube-shaped cloth.
Don’t want any holes in the bottom of your tote? Hand-stitch with a needle and thread or use a sewing machine.
Want to make the bag but don’t want to keep it? Personalize it and gift it to family and friends.

WHAT THIS TEACHES:

Repurpose and upcycle the materials you have at home to make a purse, grocery bag, shopping bag, beach bag, carry-all! There are a finite amount of resources on the planet so the more we can rethink, refuse, reduce, reuse, refurbish, repair, repurpose, and recycle, the better for everyone including wildlife and the environment!

Skills: Creativity, scissor practice, fine motor skills, knot tying


Week 20 – Duck in a Cup

Materials:

  • Plastic cup
  • String
  • Wet paper towels
  • Drill or tool to punch a hole in the bottom of the cup
  • Paper clip

Instructions:

  1. Drill or punch a hole in the center of the bottom of the cup. The hole needs to be big enough to put the string through.
  2. Tie one end of the string to the paper clip.
  3. Push the other end of the string through the hole in the bottom of the cup. The paper clip will stop the string from pulling all the way through.
  4. Hold your Duck In A Cup in one hand. This will allow the string to dangle beneath the cup.
  5. Wrap the wet paper towel around the string and pull down firmly in sharp little movements.
    Your Duck In A Cup should start quaking!

Click here to watch a 30 second video if you need help!


Week 19 – Build a Bridge Challenge!

You can build your own bridge with just toothpicks and mini marshmallows.

What you need:

  • Toothpicks
  • Mini marshmallows
  • Paper plates

Steps:

1. Place two marshmallows with the bases flat on your work surface. Insert one end of a toothpick into the center of each marshmallow to create a barbell shape. Insert another toothpick in each marshmallow at a 45-degree angle to form a triangle. Insert both bare ends of the toothpicks into another marshmallow to complete the triangle.

2. Insert a toothpick into one of the base marshmallows of the first triangle at a 45-degree angle and another toothpick into the side of the top marshmallow. Insert both of the new toothpicks’ bare ends into a new marshmallow. This will create a second inverted triangle. Repeat this process until you have three upright and two inverted triangles that form a trapezoidal shape.

3. Repeat the triangle making process from step 1 to create another matching trapezoidal shape. This will run parallel to the first and will be the second side of your span.

4. Connect the two sides of the bridge using a total of seven toothpicks to run across from marshmallow to marshmallow. Look down from an overhead view to check that you have three squares at the base and two at the top.

5. Extend the length of your bridge if desired by repeating steps 1 to 4.

Challenge: 

How much weight can your bridge withstand? Stack paper plates on top of your bridge one at a time and see how many yours can hold!


Week 18 – Build a Tabletop Hovercraft!

You will need:

  • An old CD or DVD disc
  • A 9” balloon
  • A pop-top cap from a liquid soap bottle or a water bottle
  • A hot glue gun

What to do

  1. If you are using the cap from a water bottle, cover the center hole of the CD with a piece of tape and poke about 6 holes in the tape with a push-pin or small nail. This will slow down the flow of air and allow your hovercraft to hover longer.
  2. Use the hot glue gun to glue the cap to the center of the CD or DVD disc. Create a good seal to keep air from escaping.
  3. Blow up the balloon all the way and pinch the neck of it. (Don’t tie it.)
  4. Make sure the pop-top is closed and fit the neck of the balloon over the pop-up portion of the cap. (This is usually easier with 2 people). 
    That’s it! When your ready to commence hovering, simply put the craft on a smooth surface and pop the top open.

HAPPY HOVERING!

How does it work?

The air flow created by the balloon causes a cushion of moving air between the disc and the surface. This lifts the CD and reduces the friction which allows the disc to hover freely. Large scale hovercraft are capable of traveling over land, snow and water.

Make it an experiment:

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does the size of the balloon affect the CDs ability to hover?

2. Does a helium balloon work better than an air filled balloon?

3. Do larger discs make better hovercrafts (plastic picnic plates, old record albums) ?


Week 17 – The Magic Ketchup Experiment

You will need:

  • A 1 liter plastic bottle or a water bottle
  • Ketchup pack from a fast food restaurant
  • Salt (using Kosher salt helps keep the water from becoming foggy)

What to do

  1. Remove any labels from the bottle and fill it all the way to the top with water.
  2. Add a ketchup pack to the bottle.
  3. If the ketchup floats, you’re all set – go to step 4. If the ketchup sinks in the bottle, go to step 5.
  4. For the floating ketchup pack simply screw the cap on the bottle and squeeze the sides of the bottle hard. If the ketchup sinks when you squeeze it, and floats when you release it, congratulations, you’re ready to show it off. If it does not sink when you squeeze it, try a different kind of ketchup pack or try a mustard or soy sauce pack.
  5. If the ketchup pack sinks, add about 3 tablespoons (45 ml) of salt to the bottle. Cap it and shake it up until the salt dissolves. (Kosher salt will keep the water from getting too cloudy, although it will usually clear up over time if using regular table salt.) Continue adding salt, a few tablespoons at a time until the ketchup is just barely floating to the top of the bottle. Once it is consistently floating, make sure the bottle is filled to the top with water, and then cap it tightly.
  6. Now squeeze the bottle. The magic ketchup should sink when you squeeze the bottle and float up when you release it. With some practice you can get it to stop in the middle of the bottle.

How does it work?

This experiment is all about buoyancy and density. Buoyancy describes whether objects float or sink. This usually describes how things float in liquids, but it can also describe how things float or sink in and various gasses.

Density deals with the amount of mass an object has. Adding salt to the water adjusted the water’s density to get the ketchup to float. Sound complicated? It is, but here’s the basics on the ketchup demo…there is a little bubble inside of the ketchup packet. As we know bubbles float, and the bubble in the ketchup sometimes keeps the heavy packet from sinking. When you squeeze the bottle hard enough, you put pressure on the packet. That causes the bubble to get smaller and the entire packet to become MORE DENSE than the water around it and the packet sinks. When you release the pressure, the bubble expands, making the packet less dense (and more buoyant) and, alas, it floats back up. This demonstration is sometimes known as a CARTESIAN DIVER.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

  • Do different food packs (ketchup, mustard, soy sauce) have the same density?
  • Does the temperature of the water affect the density of the ketchup packet?
  • Does the size of the bottle affect how much you have to squeeze to get the packet to sink?

Week 16 – Make a paper clip float

You will need:

  • clean dry paper clips
  • tissue paper
  • a bowl of water
  • pencil with eraser

What to do:

  1. Fill the bowl with water. Try to make the paper clip float…not much luck, huh?
  2. Tear a piece of tissue paper about half the size of a dollar bill
  3. GENTLY drop the tissue flat onto the surface of the water
  4. GENTLY place a dry paper clip flat onto the tissue (try not to touch the water or the tissue)
  5. Use the eraser end of the pencil to carefully poke the tissue (not the paper clip) until the tissue sinks. With some luck, the tissue will sink and leave the paper clip floating!

How does it work?

How is this possible? With a little thing we scientists call SURFACE TENSION. Basically it means that there is a sort of skin on the surface of water where the water molecules hold on tight together. If the conditions are right, they can hold tight enough to support your paper clip. The paperclip is not truly floating, it is being held up by the surface tension. Many insects, such as water striders, use this “skin” to walk across the surface of a stream.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. How many paperclips can the surface tension hold?

2. Does the shape of the paperclip affect its floating ability?

3. What liquids have the strongest surface tension?

4. Can the surface tension of water be made stronger? (try sprinkling baby powder on the surface)

 


Week 15 – Bend Water With Static ElectricityBend Water With Static Electricity - ScienceBob.com

You will need:

  • A dry plastic comb
  • An indoor faucet
  • A head full of clean dry hair.

What to do

1. Turn on the faucet and slowly turn down the water until you have a VERY thin stream of water flowing.

2. Take the plastic comb and brush it through your hair ten times.

3. Now slowly bring the comb close the the flowing water, (without actually touching the water) If all goes well, the stream of water should bend towards the comb! Magic you ask? Not really.

How does it work?

When you brushed that comb through your hair, tiny parts of the atoms in your hair, called ELECTRONS, collected on the comb. These electrons have a NEGATIVE charge. Remember that, its important. Now that the comb has a negative charge, it is attracted to things that have a POSITIVE charge. It is similar to the way some magnets are attracted to certain metals.

When you bring the negatively charged comb near the faucet it is attracted to the POSITIVE force of the water. The attraction is strong enough to actually pull the water towards the comb as it is flowing! If you want to try another experiment with your comb, tear up pieces of tissue until they are as a small as you can get them…I mean really small! Then charge your comb again by brushing it through your hair, and bring it close to the tiny pieces of tissue. If the pieces are small enough they will jump off the table to the comb the same way that the water was pulled to the comb. It is all thanks to the wonders of static electricity.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does water temperature affect how much the water bends?
2. Does the size of the comb affect the static power?
3. Does the amount of moisture in that air affect the static power? Try it after someone has taken a shower in the room.
4. Does the material that the comb is made of affect the static power?


Week 14 – Fluffy slime recipe

  • 3-4 Cups of Foam Shaving Cream
  • 1/2 cup of Elmers Washable School Glue
  • 1/2 Tsp of Baking Soda
  • 1 Tbsp of Saline Solution
  • Food coloring and glitter optional!

Week 13 – Clean pennies with vinegar

You will need:

  •  A few old (not shiny) pennies
  •  1/4 cup white vinegar
  •  1 teaspoon salt
  •  Non-metal bowl
  •  Paper towels

What to do:

  1. Pour the vinegar into the bowl and add the salt – stir it up.
  2. Put about 5 pennies into the bowl and count to 10 slowly.
  3. Take out the pennies and rinse them out in some water. Admire their shininess!

How does it work?

There is some pretty fancy chemistry going on in that little bowl of yours. It turns out that vinegar is an acid, and the acid in the vinegar reacts with the salt to remove what chemists call copper oxide which was making your pennies dull. You’re not done yet, though, lets try another experiment:

Add more pennies to the bowl for 10 seconds, but this time , don’t rinse them off. Place them on a paper towel to dry off. In time the pennies will turn greenish-blue as a chemical called malachite forms on your pennies. But wait, you’re still not done yet.

Place one or two nuts and bolts in the vinegar and watch – they may become COPPER in color! The vinegar removed some of the copper from the pennies, if there is enough copper in the vinegar, the copper will become attracted by to the metal in the nuts and bolts and they will take on a new copper color – cool.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Will other acids (like lemon juice or orange juice) work as well?

2. Does this cleaning chemistry work on other coins?

3. Do other amounts of salt make a difference in the chemistry of the experiment?


Week 12 – TRY SOME LAVA IN A CUP

You will need:

  •  A clear drinking glass
  •  1/4 cup vegetable oil
  •  1 teaspoon salt
  •  Water
  • Food coloring (optional)

What to do

  1. Fill the glass about 3/4 full of water.
  2. Add about 5 drops of food coloring – I like red for the lava look.
  3. Slowly pour the vegetable oil into the glass. See how the oil floats on top – cool huh? It gets better.
  4. Now the fun part: Sprinkle the salt on top of the oil. Watch blobs of lava move up and down in your glass!
    If you liked that, add another teaspoon of salt to keep the effect going.

How does it work?

So what’s going on? Of course, it’s not real lava but it does look a bit like a lava lamp your parents may have had. First of all, the oil floats on top of the water because it is lighter than the water. Since the salt is heavier than oil, it sinks down into the water and takes some oil with it, but then the salt dissolves and back up goes the oil! Pretty cool huh?

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. How long will the effect go on if you keep adding salt?

2. Do different kinds of food oil give different effects?

3. Will other substances (sand, sugar. etc.) work the same as salt?

4. Does the height or shape of the glass affect the experiment?


Week 11 – Add Color To Flowers Using Science

Many florists sell colored carnations, but I think it is more fun to make your own! And you can learn a little something about plants in the process. Best of all, you can make the flowers just about any color you want. Start off with some white carnations from your local florist. We paid about $1.00 each here in the US. (If you just want to demonstrate how plants transport water, and watch color move through leaves, you can also perform this experiment using celery.) You will also need:

  • Food coloring
  • Some small cups
  • Water

Decide what colors you would like the flowers to be and then add that color to your glass. You will need to add enough food coloring to create a strong color in the water, just a few drops of coloring will not have much of an effect. (Our blue looked more like black after adding enough color.)

Snip the last centimeter of your carnation steam and place the stem in the colored water. Now just wait. Over the next day you will see signs of the coloring emerge in the petals, and even in the leaves. Our experiments have shown that sometimes the color emerges within a few hours, other times it takes a day or two. You can make green flowers for St Patrick’s day, red for valentines…you get the idea.

So how does it work?

This is the science of TRANSPIRATION. It basically means that the plant draws water up through its stem. The water is then evaporated from the leaves and flowers through openings know as stomata. As the water evaporates, it creates pressure that brings more water into the plant – similar to drinking from a straw. Some trees can transpire dozens (even hundreds) of gallons of water on a hot day. How fast a plant transpires depends on temperature, humidity, and even wind. You may want to set up an experiment that tests the transpiration rate of the flowers by placing your plant-coloring set-up in different areas (sunny & dark, windy& still, dry & humid) and see which flower ends up with the most color – more color=more transpiration.

By the way, most flower shops do not color their flowers this way. There are many different breeds of flowers that are capable of producing a wide variety of flower colors. But we still think this way is more fun. 


Week 10 – A color symphony!

You will need:

  • A flat tray (like a cookie baking tray)
  • Food coloring (at least 3 different colors)
  • Whole milk – low fat milk will not work for this experiment
  • Liquid soap used for washing dishes

What to do:

  1. Carefully pour the milk into the tray so that it just covers the bottom
  2. Add about 6-8 drops of different colored food coloring onto the milk in different spots
  3. Add about 5 drops of the liquid soap onto the drops of food coloring and watch the show!
  4. To clean up, simply pour the colored milk down the drain. (don’t drink it!)

How does it work?

So you know where the color comes from, but why milk and liquid soap? The main job of dish soap it to go after fat and break it down. Usually the fat is on dishes from the food we eat, but fat is also in whole milk. When you drop the liquid soap onto the tray, it tried to break down the fat in the milk. While it was doing that, it caused the colors to scatter and mix creating a very colorful display. Have fun!

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. What liquid dish soap works the best?

2. Does the shape of the tray affect the reaction?


Week 9 – Make your Own Volcano!

https://sciencebob.com/make-your-own-volcano

You will need:

  • A volcano – Use paper mache, plaster, clay or if you’re in a hurry to make your volcano, use a mound of dirt outside.
  • A container that 35mm film comes in, and old pill bottle, a baby food jar, or similar size container.
  • Red and yellow food coloring (optional)
  • Vinegar
  • Liquid dish washing soap

What to do:

  1. Go outside or prepare for some clean-up inside
  2. Put the container into the volcano at the top
  3. Add two spoonfuls of baking soda
  4. Add about a spoonful of dish soap
  5. Add about 5 drops each of the red and yellow food coloring
  6. Now for the eruption!: Add about an ounce of the vinegar into the container and watch what your volcano come alive.

A VOLCANO is produced over thousands of years as heat a pressure build up. That aspect of a volcano is very difficult to recreate in a home experiment. However this volcano will give you an idea of what it might look like when a volcano erupts flowing lava. This is a classic experiment in which a CHEMICAL reaction can create the appearance of a PHYSICAL volcano eruption. You should look at pictures of volcanoes to be familiar with the different types. (A SHIELD volcano, for example is the most common kind of volcano, and yet few people know about them) The reaction will bubble up and flow down the side like a real volcano (only much faster!) Look for videos of volcanoes erupting and be sure that you understand how heat and pressure work to really make volcanoes erupt.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does vinegar temperature affect how fast the volcano erupts?
2. Does the shape of the volcano affect the direction the eruption travels?
3. What can be added to the “lava” to slow it down and make it more like real lava?
4. What combination of vinegar and baking soda creates the biggest eruption?


Week 8 – The exploding lunch bag!

https://sciencebob.com/the-exploding-lunch-bag

You will need:

  • One small (sandwich size) zip-lock bag – freezer bags work best.
  • Baking soda
  • Warm water
  • Vinegar
  • Measuring cup
  • A tissue

What to do:

  1. Go outside – or at least do this in the kitchen sink.
  2. Put 1/4 cup of pretty warm water into the bag.
  3. Add 1/2 cup of vinegar to the water in the bag.
  4. Put 3 teaspoons of baking soda into the middle of the tissue.
  5. Wrap the the baking soda up in the tissue by folding the tissue around it.
  6. You will have to work fast now – partially zip the bag closed but leave enough space to add the baking soda packet.
  7. Put the tissue with the baking soda into the bag and quickly zip the bag completely closed.
  8. Put the bag in the sink or down on the ground (outside) and step back. The bag will start to expand, and expand, and if all goes well…POP!

How’s it work?

Cool huh? Nothing like a little chemistry to to add fun to a boring afternoon. What happens inside the bag is actually pretty interesting – the baking soda and the vinegar eventually mix (the tissue buys you some time to zip the bag shut) When they do mix, you create an ACID-BASE reaction and the two chemicals work together to create a gas, (carbon dioxide – the stuff we breathe out) well it turns out gasses need a lot of room and the carbon dioxide starts to fill the bag, and keeps filling the bag until the bag can no longer hold it any more and, POP! Be sure to clean up well and recycle those plastic bags…have fun!

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

  • Will different temperature water affect how fast the bag inflates?
  • What amount of baking soda creates the best reaction?
  • Which size bag creates the fastest pop?
    P.S. If you like this experiment, try the Film Canister Rocket. (Next week!)

Week 7 – Fantastic Foamy Fountain

You will need:

  • A clean 16 ounce (473 ml) plastic soda bottle or a water bottle.
  • 20-Volume hydrogen peroxide liquid (20-volume is a 6% solution which is stronger than what you find in most pharmacies. It is typically used for lightening hair and is found at many beauty supply stores. You can use the 3% hydrogen peroxide found in pharmacies, but the reaction will be a bit smaller)
  • 1 Tablespoon (15ml – one packet) of dry yeast
  • 3+ Tablespoons (15 ml) of warm water
  • Liquid dish washing soap
  • Food coloring
  • Small cup
  • Funnel
  • Safety goggles
  • Adult help
    NOTE: The foam could overflow from the bottle, so be sure to do this experiment on a washable surface, or place the bottle on a tray.
  • CAUTION: The unreacted hydrogen peroxide can irritate skin and eyes. Read the safety information on the hydrogen peroxide bottle and be sure to wear safety goggles.

What to do

  • Use a funnel to carefully pour 1/2 cup (118 ml) of the hydrogen peroxide liquid into the bottle
  • Add about 10 drops of your favorite food coloring into the bottle.
  • Add about 1 tablespoon (15ml) of liquid dish soap into the bottle and swish the bottle around a bit to mix it.
  • In a separate small cup, combine the warm water and the yeast together and mix for about 30 seconds. It should be about the consistency of melted ice cream – add a bit more warm water if needed.
  • Now the adventure starts! Use the funnel to pour the yeast-water mixture into the bottle and watch the foaminess begin!

Can I touch the foam?

The reaction typically breaks down the hydrogen peroxide so you are left with mostly just soapy water and yeast. There can, however be un-reacted peroxide which could irritate skin and eyes. For that reason, it is recommended you do not touch the foam.

(If you use the 3% hydrogen peroxide found in most pharmacies, then the foam can be touched safely.)

How does it work?

Foam is awesome! The foam you made in this classic Elephant’s Toothpaste reaction is extra-special because each tiny foam bubble is filled with oxygen. The yeast acted as a catalyst; a catalyst is used to speed up a reaction. It quickly broke apart the oxygen from the hydrogen peroxide. Because it did this very fast, it created lots and lots of bubbles. Did you notice the bottle got warm. Your experiment created a reaction called an Exothermic Reaction – that means it not only created foam, it created heat! The foam produced is just water, soap, and oxygen so you can clean it up with a sponge and pour any extra liquid left in the bottle down the drain.

This experiment is sometimes called “Elephant’s Toothpaste” because it looks like toothpaste coming out of a tube, but don’t get the foam in your mouth!

Make it an experiment:

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

Does the amount of yeast change the amount of foam produced?
Will the experiment work as well if you add the dry yeast without mixing it with water?
Does the size of the bottle affect the amount of foam produced?


Week 6 – Build a Fizz Inflator

Build a Fizz Inflator

You will need:

  • One small empty plastic soda or water bottle
  • 1/2 cup of vinegar
  • Small balloon
  • Baking soda
  • Funnel or piece of paper

What to do

  1. Carefully pour the vinegar into the bottle.
  2. This is the tricky part: Loosen up the balloon by stretching it a few times and then use the funnel to fill it a bit more than half way with baking soda. If you don’t have a funnel you can make one using the paper and some tape.
  3. Now carefully put the neck of the balloon all the way over the neck of the bottle without letting any baking soda into the bottle.
  4. Ready? Lift the balloon up so that the baking soda falls from the balloon into the bottle and mixes with the vinegar. Watch the fizz-inflator at work!

How does it work?

The baking soda and the vinegar create an ACID-BASE reaction and the two chemicals work together to create a gas, (carbon dioxide) Gasses need a lot of room to spread out and the carbon dioxide starts to fill the bottle, and then moves into the balloon to inflate it.

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

Does water temperature affect how fast the balloon fills up?
Does the size of the bottle affect how much the balloon fills?
Can the amount the balloon fills-up be controlled by the amount of vinegar or baking soda?


Week 5 – Make your own rock candy!

Make your own rock candy!

You will need:

  • A wooden skewer (you can also use a clean wooden chopstick)
  • A clothespin
  • 1 cup of water
  • 2-3 cups of sugar
  • A tall narrow glass or jar

What to do

  • Clip the wooden skewer into the clothespin so that it hangs down inside the glass and is about 1 inch (2.5 cm) from the bottom of the glass. (as shown)
  • Remove the skewer and clothespin and put them aside for now.
  • Get a helpful adult! Pour the water into a pan and bring it to boil.
  • Pour about 1/4 cup of sugar into the boiling water, stirring until it dissolves.
  • Keep adding more and more sugar, each time stirring it until it dissolves, until no more will dissolve.
  • This will take time and patience and it will take longer for the sugar to dissolve each time.
    Be sure you don’t give up too soon. Once no more sugar will dissolve, remove it from heat and allow it to cool for at least 20 minutes.
    NOTE: While it is cooling, some people like to dip half of the skewer in the sugar solution and then roll it in some sugar to help jump start the crystal growth. If you do this, be sure to let the skewer cool completely so that sugar crystals do not fall off when you place it back in the glass.
  • Have your friendly ADULT carefully pour the sugar solution into the jar almost to the top. Then submerge the skewer back into the glass making sure that it is hanging straight down the middle without touching the sides.
  • Allow the jar to fully cool and put it someplace where it will not be disturbed.
  • Now just wait. The sugar crystals will grow over the next 3-7 days.
    Want colored rock candy? Add food coloring to your sugar water and make sure sure that it is pretty dark in color for the best result.

How does it work?

When you mixed the water and sugar you made a SUPER SATURATED SOLUTION. This means that the water could only hold the sugar if both were very hot. As the water cools the sugar “comes out” of the solution back into sugar crystals on your skewer. The skewer (and sometimes the glass itself) act as a “seed” that the sugar crystals start to grow on. With some luck and patience you will have a tasty scientific treat! Enjoy!


Week 4 – A Density Experiment You Can Drink
!
https://sciencebob.com/a-density-experiment-you-can-drink/       

Density is a fascinating and sometimes tricky idea to understand. This Drink of Density will help bring home the idea of density in liquids, not to mention it looks cool when your all done, it’s tasty, and it’s even good for you – what more could you ask for in a science activity!

You will need:

  • Juices that have different density levels. (see below for a simple explanation of density) The density of a juice is often determined by how much sugar or fruit is in it – the more sugar or fruit, the more dense the juice is. Powdered and canned juices do not work well for this experiment since they are almost entirely water. You will have to do some experimentation to find juices that are colorful and give a nice display of density, and that’s half the fun.
  • A narrow glass (the more narrow it is, the easier it is to separate the density levels)
  • Eye dropper or turkey type baster.

What to do:

Before you begin, you can guess which juices you think will be more dense and form a hypothesis of how the levels of your Drink of Density will turn out. Check the number of ingredients, the sugar content, and the water content to help you out.
In order to display your density levels, you will need to find out which of your juices are the most and least dense.

  1. Pour one of your juices into the narrow glass to fill it about 1 inch (2.5 cm) high.
  2. Fill a dropper with another juice and slowly drop it onto the inside of the glass so that it runs down the side of the glass.
  3. Watch the juice to see if it goes below or above the juice in there. (if it simply mixes with the juice and does not go above or below, it has the same density as the juice and you will need to move on to your next juice.
  4. Continue experimenting with other juices to determine which juices go to the bottom (more dense) and which ones go to the top (least dense.)
  5. Once you have the densities determined, start over with a clean glass and use the dropper for each level to create your final Drink of Density!
  6. Note: In case you were wondering, the juices in the photo are (top) Tropicana Pomegranate-Blueberry, (middle) Tropicana Pure Premium Orange Juice, (bottom) Nature’s Promise White Grape (33 grams of sugar in 6.75 ounces!)

How Does It Work?

The density of liquids demonstrates the the amount of “stuff” (atoms, mass) that are present in a particular volume of the juice. In other words, if you have cup with 200ml of plain water, and a cup with 200 ml of water that has lots of sugar dissolved in it, the cup of sugar water will be heavier even though they are the same volume of liquid – the invisible sugar molecules are dispersed in the water, making it heavier (more dense.)


(Week 3) Eggshell Geode Crystals

https://sciencebob.com/eggshell-geode-crystals/

This project nicely demonstrates how real-life geodes are formed in igneous and sedimentary rock. It also demonstrates super-saturated solutions and shows a nice variety of crystal shapes and formations.

YOU WILL NEED:

  • clean eggshells
  • water
  • a variety of soluble solids: table salt, rock salt, sugar, baking soda, Epsom salts, sea salt, borax, or cream of tartar
  • small heat proof containers (coffee cups work well)
  • spoons
  • food coloring
  • egg cartons and wax paper or mini-muffin tins

WHAT TO DO:

  1. Crack the eggs for this project as close to the narrow end as possible. This preserves more egg to use as a container for the solution.
  2. Clean the eggshells using hot water. The hot water cooks the lining and allows you to pull the skin (egg membrane) out of the inside of the egg using your fingers. Make sure to remove all the egg membrane, if any membrane stays inside the shell it is possible that your eggshell will grow mold and your crystals will turn black.
  3. Use an egg carton lined with waxed paper or mini-muffin tins to hold the eggs upright.
  4. Use a saucepan to heat the water to boiling. .
  5. Pour half a cup to a cup of water into your heatproof container. If you poured half a cup of water into the container, add about a ¼ cup of solid to the water. Stir it until it dissolves. Likewise if you used a cup of water, add about ½ a cup of solid to the water. You wanted to add about half again the volume of the water as a solid to the mixture. When the initial amount of solid is dissolved continue adding small amounts of the solid until the water is super-saturated. Super-saturated simply means the water has absorbed all it is able to absorb and any solid you add will not dissolve.
  6. Add food coloring.
  7. Carefully pour your solution into the eggshell, filling it as full as possible without over-flowing it or causing it to tip.
  8. Find a safe place to put your shells while the water evaporates. Crystals will form inside the eggshells as the water evaporates.

How does it work?

Dissolving the crystals in hot water created what is called a “super-saturated solution.” This basically means that the salts took advantage of the energy of the hot water to help them dissolve until there was no more space between molecules in the solution. As the solution cooled, the water lost its energy and the crystals are forced from the solution to become a solid again. Since this happens slowly along with the evaporation, the crystals have time to grow larger than they were when the experiment started. Natural geodes in rock are form in much the same way as mineralized water seeps into air pockets in rock. This is also how rock candy crystals are formed.


(Week 2) Homemade Ice Cream

https://sciencebob.com/easy-to-make-ice-cream-in-a-plastic-bag/

You will need:

  • 4 oz of milk
  • 4 oz of cream
  • 1/4 tsp of vanilla (or use other flavors usually found near the vanilla in a grocery store – you can use chocolate syrup for chocolate ice cream)
  • 4 tsp of sugar
  • A few drops of food coloring (optional – if you want colorful ice cream)
  • Lots of ice
  • Lots (half cup) of salt. Rock salt (sold at hardware stores) works best.
  • Small (quart size) zip-lock freezer bag
  • Large (gallon size) zip-lock freezer bag

What to do:

  1. Put the milk, cream, flavoring, coloring, and sugar into the SMALL zip-bag and zip it shut (be sure it is zipped up and closed completely)
  2. Put about a cup of ice into the large bag and the cover the ice with a small handful of salt. Put the small bag with your ingredients into the larger bag.
  3. Add some more ice and then some more salt. Keep adding salt and ice until the bag is almost full.
  4. Zip it shut (be sure it is zipped) and then carefully hold opposite sides of the bag and shake the bag back and forth (like your steering a car) for about 5-8 minutes.
  5. Open the larger bag and take out the smaller bag – it should be full of ice cream! Rinse off the bag under running water to remove any salt that may be near the opening of the bag.
  6. Open and enjoy!

The Science of Ice Cream

When you added salt to the ice, the chemistry between the two forced the ice to melt. Before the ice could melt though, it needed to borrow heat from objects that surround it. This is called an ENDOTHERMIC process. Since your ingredients are not as cold as the ice, it borrowed heat from your ingredients making them colder! When they get colder, they freeze up into ice cream. Yum!


(Week 1) The Egg Drop Challenge

https://sciencebob.com/try-the-egg-drop-challenge/

You will need:

  • 1 plastic cup of water with a mouth wide enough to fit the egg.
  • 1 10” (25 cm) piece of cardboard or a small tray with a SMOOTH bottom
  • 1 cardboard tube (paper towel or toilet paper tubes work well)
  • 1 Egg (uncooked for more drama)

What to do:

  1. Place the tray centered over the cup
  2. Place the tube on its end in the center of the tray
  3. Place the egg horizontally on the tube
  4. When ready, strike the tray hard enough with your palm to send the tray flying, but not so hard you hit the glass of water. If all goes well, the tray and paper tube will go flying, but the egg will safely drop into the water.

How does it work?

INERTIA describes an object in terms of how much energy is needed to move it or stop it from moving. Since the tray and tube are very low mass (lightweight,) they have very little inertia, and will easily move out of the way.
The egg, however, is heavier (has more inertia) and so it is not easily moved, leaving it in place for gravity to bring it down into the cup.