Not only is teaching your toddler “hot” and “cold” great for learning opposites, there is a huge safety incentive as well. For this activity, I just used 2 of those Pyrex gel pack thingys that came with my Pyrex travel carrier that can either go in the freezer or microwave. I put one in the freezer for several hours and the other in the microwave long enough to make it hot (and make him want to remove his hand immediately) but not too hot where it could burn him.
After you initially introduce the words “hot” and “cold”, then encourage your child to say them aloud. After that, ask him/her to point to the “hot” one and then point to the “cold” one. Involve your older child by playing a guessing game. These were all my intentions for the video, but things didn’t go exactly as planned (i.e. the boys wanting to be the frozen pack in their mouths).