Homemade "lava lamp"

So is today more of a science day or more of a hippie day? Good news, you are in luck. You can do both. Plus, there is the added bonus of downing your favorite soda in the name of science. "Sorry, mommy needs Dr. Pepper today so you can have fun with the bottle later dear."

Materials for the "lava lamp"
-plastic bottle
-vegetable oil
-water
-liquid food coloring
-funnel
-plastic cup

Directions:
Fill the plastic cup with water, add food coloring and mix.
Pour vegetable oil into the empty bottle until it is 1/2 to 3/4 full. (use the funnel)
Add the colored water to the bottle.
Put the cap on the bottle tight- don't stir or shake it (not yet any ways- do that later for fun)

(Something else we've done to "recycle")