Raccoon loves glass jars. He has a collection in a plastic basket, each one filled with water. I recently bought some food coloring because I often see it on the list for at-home activities. I wasn't sure how he was going to react to me coloring the water in his jars; he tends to like everything to stay the way it was originally. This is one area where his phenomenal memory definitely works against us. But I went ahead anyway, and it turns out that he loved it. My favorite was the jar that looked black just sitting on the table, but held up to the window was clearly purple.
We also did the vinegar and baking soda experiment, except it turns out that I had too much vinegar and not enough baking soda. My budding scientist was very disappointed that it didn't explode!