Next, we set got into partnerships and set up our lab. We needed a laptop, two temperature probes, our water-holding device, and some icy cold and hot tap water. For our water-holding device, I used old cookie dough containers (the big ones) and taped a red Solo cup inside with some amazingly strong double-sided sticky tape. The inner Solo cup would hold the hot tap water (and a drop of red food coloring), and the outer cookie dough container held the icy cold water (with a drop of blue food coloring). Before letting kids have their cold and hot water, we predicted what we thought would happen when the two were put together in the containers. Many thought they would see steam or smoke. Some just expected the temperatures to even out.
As soon as students were given their filled containers, they rushed to plunge their temperature probes into the respective sections and begin collecting data (we used Logger Lite to record data). Students quickly noticed that the hot water was cooling down and the cold water was warming up. We discussed what we thought might happen next. Some thought they would become the same temperature and then start reversing their temperatures (making an "X" with the line graph). Some thought it would level off midway between the two starting temperatures. To our collective surprise, they did begin to reverse themselves! The cold water ended up becoming warmer than the warm water! At first, we couldn't explain it scientifically. Eventually, we decided that the outer water was able to warm up from the heat transferring through the cookie container from the air, but the inner cup was surrounded by water, so it didn't have the same opportunity to be warmed by air (since air changes temperature more quickly/easily than water). We liked that theory and settled on it. We had never experienced this phenomenon using standard thermometers, because they are not nearly as accurate as these temperature probes are!!!
At various times during the lesson, I wanted to move on to something else (still related to this lesson) but my students wouldn't let me because they were having so much fun making new discoveries and trying to explain what they were observing. The discussions they had were very intellectual and made me proud to see them learning so much without the need for a teacher to be teaching! This lesson had some great critical thinking components, collaborative discussions, and reflection opportunities. It used guided inquiry as its delivery format, which meant that the students got to do hands-on experimenting with guidance. They loved it!