1. The problem statement, all variables and given/known data This is a question for 10 year old but I have a problem understanding why the answer is so. (The student asked me this.) There are two similar containers, X and Y, with 500 ml of boiling water. X is an aluminium container. Y is a plastic container. They are then covered with a sheet of glass and left in a room for 30 minutes. The answer options are 4 graphs of temperature against time. 2. Relevant equations 3. The attempt at a solution (I have taken a photo of the question in the worksheet but can't seem to upload the image here. It would be better to show the graphs, but since I can't upload it, I'm describing them here.) Of the 4 options, I've eliminated 2 of them as they started X and Y at different temperatures. In options 3 and 4, they start at the same temperature. In option 3, the temperatures for X and Y gradually fall over time, with X at faster rate and ends at lower temperature than Y after a certain time. In option 4, X and Y are straight lines from the same temperature. However, the temperature of X falls over time (negative gradient) and the temperature of Y increases over time (positive gradient). My answer would be option 3 as heat would dissipate faster from the aluminium container. The final temperature of the water in both containers would be lower than the initial temperature. However, the answer (given by the teacher apparently) is option 4. This means that after 30 minutes, the temperature of the water in the plastic container is higher than the initial temperature. So the question is, why is this so? Help explain please?