Tuesday, January 22, 2013

Lava in a Cup Experiment

My 3rd graders needed to learn about mixtures while they were studying matter, so I thought doing an experiment with lava lamps would be a great way to do that.

Similar to when we did the magic milk experiments, I started with the "control" experiment for them to wonder about... Here is it, in case you need it:

  • clear, plastic cup {9 oz works great}
  • water
  • food coloring {any color works}
  • vegetable oil
  • salt
  1. Fill the cup about 1/2 with water. 
  2. Add about 5 drops of food coloring.
  3. Add enough vegetable oil to make your cup about 3/4 full. 
  4. Pinch some salt between your fingers and sprinkle it into the cup. 
  5. Watch as a "lava lamp blob" forms and moves!
I think the place where I originally read about this activity suggested putting the oil in before the food coloring. But, if I remember correctly, it produced a BIG FAT DUD experiment when I tried that with my kids.

Just like with the magic milk activity, I let kids "wonder" aloud about things concerning this demo. Afterwards, I let the kids run free and do their own thang to investigate as they pleased. Some used timers to see how long the effect would keep going. Some added sugar instead of salt. Some used corn oil instead of vegetable oil -- the choice was up to them.

Here's a lava lamp in the making:

 The kids were fascinated with just oil + water alone, but add in food coloring and salt to make the blobs "dance," and you've got yourself a sure recipe for fun. :) Maybe one of these days when I can get some extra time, I'll modify the experiment sheets I created and post them for your downloading pleasure. :)

Other ways you could use this activity:
  • My 1st and 2nd graders have to learn about ways objects move. These blobs of food coloring move in such unique ways, I think this lesson would be fantastic for them!
  • While watching for ways the color moves, why not work on adjective skills?
  • Practice the scientific method -- always!

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