Level: Brownies

Girls will earn the Science Wonder Try-It after completing all of the activities.

Today we are going to be scientists and you will earn the Science Wonder Try-It. Do any of you know what a scientist is? Can you name a scientist? Louie Pastur was a scientist. He invented the pasteurization of milk so that we can drink it. Do you know of anyone else? How many of you know what an experiment is? An experiment is a test under controlled conditions that is made to demonstrate a known truth or determine the value of something previously untried, such as conducting a test. We are going to do four experiments today involving crystals, bubbles, magnets, and static electricity.

When we do experiments, we use many things to get the results we want. We use our materials. Like in our first experiment today, we are going to use water, glycerine, and dishwashing liquid. But other things effect our experiments, too. Do you know any of these things? (Temperature, Weather, light, poor materials, etc.) As scientists, is it possible that one of us can make a mistake in the experiment, causing it to be unsuccessful? So as we work together today, let’s try to keep these things in mind. If we can’t get the results we want from an experiment, it does not mean that we failed. It just means there was a mistake somewhere, in either our materials, our efforts, or in our hypothesis (what we thought would happen). We can then explore why our results were not correct. Is everyone ready? Let’s get started on our experiments!

Before we begin, we need to set up the materials for our last experiment so the solution can set.

What we need:

• Newspaper or plastic to prevent messes

• 2 spoons or stirrers per girl

• 3 ounce plastic Dixie cups (2 per girl)

• Fast-rising, dry yeast (approx. 2 teaspoons per girl)

• Sugar (approx. 2 teaspoons per girl)

• Measuring spoons

• ¼ cup measure

• Small Ziploc resealable bags

• Matches

• Cup to pour water

• Container/Bowl for warm water (110-120 degrees)

• Thermometer

Does anyone know what yeast is used for? It is used to make bread and in other forms of baking. Look at the yeast. This is a living organism. It can eat food, grow and make other products.

Demonstrate this first part of the experiment to the group as a whole. Check to make sure none of the girls know they are allergic to yeast before they handle it. Cover the work area with newspaper or plastic.

1. Put one teaspoon of yeast into a re-sealable plastic bag.

2. What do living things need to stay alive? Have the girls mention what they need to live. First they need food. Let’s give this yeast some food. What do you think yeast likes to eat? Sugar, of course! Put two teaspoons of sugar into the bag.

3. What else do living things need? Your right, water. Add ¼ cup of warm (120 degree) water to the bag.

4. The yeast also needs a place to live that is warm enough. Close the bag while pushing out all of the air. Show the girls that there is no air in the bag and put the bag into a container of 120 degree water. Now move onto the next step and let the yeast grow for about five minutes or until foaming.

5. Give each girl two cups. One will be labeled "S". You can label the cups ahead of  time or have the girls do it. Put 1 teaspoon of yeast into each cup.

6. Add 2 teaspoons of sugar to the cups labeled "S".

7. Add ¼ cup water to both cups and have the girls stir with a stirrer or spoon until the yeast dissolves.

8. Move away from the cups, so they remain undisturbed, and return to the bag of yeast experiment. The bag should be full of gas. Shake the bag to break up the foam but do not open it yet.

9. What happened to the bag? Do you know what caused this? Yeast makes a gas called carbon dioxide when it grows. When our yeast grew, it made enough carbon dioxide to fill up the bag.

10. Either set the bag on a flat surface or have an adult hold the bag open for you. Light a match and lower it into the gas in the bag (Do not drop it). The match will not stay lit because carbon dioxide is heavier than air, so it stays in the bag. Matches will burn in air but not in carbon dioxide.

11. Squeeze the bag shut to remove the gas. Show the girls the gas is gone and open the bag. Repeat the match test to show that air has replaced the gas and the match will stay lit.

12. If ten to fifteen minutes has passed, then return to the cups. The "S" cups should + have began to foam. If not keep the girls busy with discussion.

13. Have the girls check their cups. Did the yeast grow with or without food? Only the cups with the sugar should grow!

Who knows what a magnet is? Do you have any at home? Where? Does anyone use magnets to put schoolwork or artwork on the refrigerator? Magnets were discovered over 4,000 years ago! They pull some objects to them because of what the object is made of. This force between the magnet and the object (the refrigerator, for example) is so strong sometimes, that it can hold objects in between them, like your papers and notes. Most magnets are made of iron and come in many different shapes. The discovery of magnets was very important as they are used to make electric motors and generators. If electricity would disappear we would have no telephones, lights, electric heat, computers, televisions!

Let’s explore what magnets are attracted to!

What we need:

1. Spread out the item for testing on the table, floor, or both (depending on group size)

2. Pass out a magnet to each girl. (If there is a larger group, have the girls work in pairs of two or three)

3. Have them touch different items you have given them to see if the magnet attract or does not attract. Encourage girls to explore outdoors as well within a limited area (weather permitting) (needs adult outside)

4. Check off on the Magnet Hunt whether the items were attracted or not. Let them test fill in other items around the Discovery Center and outdoors (if weather permits).

Come back together. Lead a discussion to see if each girl/team got the same results on the Magnet Hunt original items. If not, take a magnet and do the test with them as a group. Have girls/teams share their results on other items they tested that were not originally on the Magnet Hunt. Explain that magnets attract to items that are iron.

Reference: http://www.science-tech.nmstc.ca

We know now that magnets are used to make electricity, but does anyone know what static electricity is? It is a special kind of electricity that can be made by rubbing some things together. Have you ever seen lighting during a storm? Lightning is a type of static electricity in the clouds. Have you ever felt a spark when you touch something after walking on a rug? This is also a form of static electricity. Or, you come inside from the cold, pull off your hat and....BOING! All your hair stands on end. What is going on here? We are going to try to make our own static electricity!

What we need:

1. Have each girl blow up one balloon and tie the ends. (may need parent assistance)

2. Rub a balloon very quickly on a wool cloth.

3. Hold the balloon over the very small pieces of shredded paper. What happens?

4. Rub the balloon with the wool cloth again.

5. Hold the balloon next to a thin stream of water from a faucet. What happens?

6. Hold the same balloon to the wall. If it has enough static electricity, it will stick. Rub the balloon on the wool cloth again to give it more static charges.

7. Have the girls blow up another balloon and tie the ends. (may need parent assistance)

8. Tie the balloons together using the string.

9. Rub both balloons on the wool cloth.

10. Holding the balloons by the string, try to make them touch. What happens?

How many of you have ever blown bubbles before? For our last experiment, we are going to try to make our own bubble solution and our own wands. Do you remember that mixture we made before we started our session? That is our bubble solution!

What we need:

1. Have the adults help you to bend each girl their own bubble wand.

2. If weather permits, take experiment outside. (If weather is poor, put girls into teams and perform small amounts of the experiments. Offer to put some of the solution in a baby jar for the troop leader to take along to use at their next troop meeting)

3. Dip your bubble wand into the pan and then gently wave it in the air.

4. Try shaping your wands into other shapes. Does your bubble change shape too?

5.  

Review with the girls about experiments (if any) that did not work. Talk again about factors that may have contributed to the error. If all experiments worked, discuss what could have happened to give them incorrect results.

Also review:

1. What is an experiment?

2. What does scientist do?

3. What is a hypothesis?

4. What experiment results were not what you thought they would be?

5. What did you learn?

This page last edited on Monday October 30, 2006.

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