For this activity you will need an empty water bottle, food coloring, vegetable oil, alka seltzer, a baking sheet, and water.
First, fill the bottle halfway with the oil, then add water to an inch or so from the top.
This is a great time to talk about your observations. Ask questions like "What do you think will happen when we add the water?" Be sure to talk about what you are observing through the whole process. "What happened? The oil and water do not mix!"
Now add some food coloring. Cut or break an antacid tablet in quarters and drop one quarter into the bottle. When the bubbling slows, add another quarter-tablet to get it started again. Biscuit loved this part of the process! She was super excited watching the bubbles rise to the top.
When the bubbles have subsided, put the cap on your bottle. You may want to glue it on.
Happy Playing and Exploring!!