Lava Lamp

I was all excited to do this activity with the kids and have them ooohhhhh and aaahhhhh.  Matthew was a bit bored {as you can see in the picture below} and Jillian had already tried it at preschool.
Good thing Sarah loved it!

First, find a jar or bottle and pour some water into the bottle.  Our bottle was small so we filled it until it was about an inch high.  Then pour vegetable oil in, leaving some room at the top.  We waited a little and watched the oil and water separate.  Then we added a bunch of food coloring {the kids put in about 6-8 drops} and watched as the drops of coloring passed through the oil to the water.



Then I broke some Alka Seltzer tablets into quarters and let them drop them in one at a time.
{for a bigger bottle you would probably want to use 1/2 a tablet} 

Then Sarah ooohhhh'd and aaahhhh'd as the red blobs and bubbles rose up through the oil!
{apparently this was still not enough excitement for Matthew}

This was a fun activity and the best part is you can keep doing it over and over.  If you have a bottle with a cap you can just store your 'lava lamps' and use them again and again!

Just don't let your kids put all their pieces of seltzer into the bottle at the same time - the kids loved all the bubbles but I had a counter of overflowed oil to clean up!

 

Idea from Science Bob