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STEM activity of the week – Fun for all ages!

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.