Add the following materials to the labeled bags:

       Bag #1: 2 t. yeast

       Bag #2: 2 t. yeast and 1/4 cup warm water

       Bag #3: 2 t. yeast, 1/4 cup warm water, and 1 T. sugar

       Bag #4: 2 t. yeast, 1/4 cup warm water, and 1 T. flour

Squeeze out as much air as you can and zip each bag. Put the bags in a warm place for 15 to 30 minutes. What changes do you notice have occurred?

2.) Every food is either acid-forming or alkalinizing. Our bodies need some of both kinds, although alkalinizing foods are better. Find out what foods are acid-based and which are alkaline-based. Which group do you eat more of? Why is too much acid harmful to the body? Do some foods change from one category to another when they are consumed?

2a. Let’s try an experiment to see how acids can break foods down. You will need a few eggs, white vinegar, a container big enough to hold all your eggs, a cover, and a large spoon. Place your eggs in the container without letting them touch. Cover the eggs with vinegar and then place the cover on the container. Place the container in the refrigerator and let the eggs sit for 24 hours.

Use the large spoon to scoop the eggs out of the vinegar. But be careful—the eggshell has been dissolving, so the egg membrane may be the only thing holding the egg together. Carefully dump out the vinegar then put the eggs back into the container and cover them with fresh vinegar. Leave the eggs in the refrigerator for another 24 hours.

Scoop the eggs out again and rinse them carefully. When you’re done, you’ll have an egg without a shell. It looks like an egg, but you’ll be able to see inside it. The membrane will flex when you squeeze it.

2b. In this experiment we will make a bag explode, so you may want to have an adult help you. You will need water, a measuring cup, zip-lock sandwich bags, paper towels, and a tablespoon of baking soda and vinegar.

Step 1: These bags can make a mess when they explode, so you might want to find a good spot to do the experiment—maybe outside or in the bathtub or sink.

Step 2: Make sure your bag does not have holes in it or it may not work. Test it by pouring water in the bag and tipping it upside down. If it does not leak, you can use the bag.

Step 3: Tear a paper towel into a 5”x5” square. Put 1 1/2 tablespoons of baking soda in the center of the square. Fold the square into three parts, like you would fold a letter, so that the baking soda is inside. Then fold that rectangle into thirds again so that the ends completely overlap in the center. This is your “time-release packet.”

Step 4: Pour 1/2 cup of vinegar and 1/4 cup of warm water into your sandwich bag.

Step 5: This part is a bit tricky. You need to drop the time-release packet into the vinegar and zip the bag closed before the fizzing gets out of control. You can zip the bag halfway closed, then stuff the packet in and zip the bag closed the rest of the way in a hurry.

Step 6: Shake the bag a little, put it in the sink or on the ground, and stand back! The bag will puff up and pop with a bang. Whooeee!