How can I keep plants cold for science project?

Question

For a science fair project we are comparing how plants grow in cold vs hot temps. I can keep the plants warm but how can I keep them cold without putting them in the refridgerator. I need a way so the get the same amount of sunlight as the warm plants

Answer 1

keep the plant in a small pot. keep the pot in a glass vessel. pour sufficient ice cubes and salt in between the two containers. insert a thermometer in it. close with a glass plate partially.

Answer 2

maybe a freezer