We did this really clever little activity last week. The kids thought it was genius and it only took minutes to set up. You can do it with all things you have in your house! I ran across it here on The Mother Huddle. Love that blog.
What you need:
spoons
cups
water
vinegar
food coloring
baking soda
What you do:
Arrange your spoons and put a few drops of food coloring in each spoon. I added more than one color in some spoons so that we would have a bunch of different colors. (you know…red + yellow = orange and all that) 
Then (using a different spoon), put some baking powder in each of your ‘food coloring spoons’ so that you can’t see what color is underneath.
Set this plate aside and gather a clear cup for as many spoons as you have. Fill each cup half way with either water or vinegar. I made more vinegar cups than I did water cups – because they are just more fun. You could really just make all vinegar cups. But, the bird actually did enjoy seeing if the cup would bubble or not bubble. The bean wanted them all to bubble and was slightly disappointed when he got a plain non-bubbling water cup.
I gave them one cup and one spoon at a time to begin, but older kids could probably handle more at once. Make sure you put them in a pan of some kind – because the bubbles do overflow.
They loved seeing if it would make bubbles or not. They loved seeing what color would magically appear. Just a fun activity.
I'm wife to wonderful hubby, mom to a bird and a bean and teacher to middle school ESL students. I love Jesus, cooking, bargains and anything crafty. 
I love this and may have to use it in my preschool classroom. Thanks!
Little scientists! Super fun!
Okay, your little girls face says it all! Thanks so much for sharing with your readers and the link :). Seeing pictures always makes my day!
Destri