This is the key to the Sinkhole in a Cup Classroom Activity -- it includes correct and anticipated answers to the lab.
In this activity, students will cuts small holes into the bottoms of styrofoam cups, and place filters (scrub pad circles work very well here) above the hole. This is to let water in, but to keep sand and undissolved sugar within it. Create a paper tube (~0.5" wide, ~2"-3" tall) and place it above the filter. Fill it with granulated sugar, and surround the with sand, with a layer on top. Drip food coloring on top of the sand (pollution), and place the cup into a bucket of water! Noticeable effects should occur in 30-40 minutes.
Click here to find and download the Question Sheet!