Melting Chocolate

During our science lesson today, we were learning to use a thermometer accurately. We conducted an experiment. We used three tubs, water, chocolate, trays, thermometers and a stopwatch. We measured out 200ml of water into  each of the three tubs. We checked the temperatures of the water. The temperature of tub one was 50 degrees celsius, tub 2 was 21 degrees celsius and tub 3 was 7 degrees celsius. We dropped the same size piece of chocolate into the trays at the same time. We made predictions about what we thought would happen to the chocolate. After five minutes, we observed each piece of chocolate in each tray. The chocolate in tub 1 had changed state from a solid to a liquid. The chocolate in tub 2 had started to melt but only a little. The piece of chocolate in tub three had not changed at all.