No one has ever counted all the bubbles. But we know a bubble means a gas is inside something else. Vinegar is a liquid, baking soda is a solid, where are the bubbles coming from?
Materials
Vinegar
Baking soda
Cookie tray, a large tray to catch the foam
Clear plastic cups, 10 to 16 ounces
Marker
Dish Detergent, for handwashing dishes in the sink, Dawn works well
Measuring spoons
Food coloring optional
Ask students to copy a simple recipe in their journals:
1 cup vinegar
1 teaspoon baking soda
We measure these, and pour the soda in the vinegar, and it starts changing fast. Students talk to each other and the class reconvenes to say simple sentences that we could write. Students write an entry in their journals and draw the picture.
Day 2
Announce that there is another recipe that the class can try. Ask the students to copy this recipe in their journals.
1 cup vinegar
1 teaspoon baking soda
1/2 teaspoon of dish detergent
But how can we test this recipe? How will we know if it’s really better or not? Write key vocabulary words when the students use one. That can be used for writing later.
(At this point I listen carefully) We could measure a cup of vinegar in each plastic cup and label one A and the other B. We could put dishsoap in B. Cup A will stay as yesterday’s original recipe. Cup B will have soap.
Then we could measure a teaspoon of baking soda onto a paper plate for A and another teaspoon of soda on a plate for B.
Stop at this point and ask what is the only difference between A and B. That discussion might be quick and simple. Everyone should agree. 3,2,1 dump the baking soda in both cups at the same time. They will want to talk about it, they should for a few minutes.
When the class regroups, ask if anyone was surprised. Did the soap make a big difference? Ask the class to take turns and tell us which recipe we liked better.
Students enter what they saw and what they learned. They read their entry to three other students. Let them draw the picture. And color it, of course, if you give a first grader a cookie..