Alternatively, have your DS come up with several questions he'd like to answer and see if he can develop a way of testing it or figuring out the answer. When my son did a project in 2nd grade, he wanted to know if hot water cools down to room temp at the same rate that cold water warms up to room temp. He designed the experiment and wrote a program in NXT-G, and using an thermometer with the NXT brick, he acquired the data, saved it to file, and DH helped him to graph it in Excel. It was a great experiment and my chemical engineer-FIL was impressed with the data. It perfectly illustrated an asymptote.
