He needs a new material to keep his cup warm longer.
The equipment needed
How We Conducted the Experiment
We wrapped each cup of water in a different material. We then placed a thermometer in each cup. We got our stopwatches and recorded 5 minutes. After each minute passed, we noted the temperature decrease. Once the five minutes were up we evaluated our results and declared what fabric insulated the water the best.
Within our group the cotton insulated the water the best. Over the five minutes there was only a 7 degrees decrease in comparison to the cloth and tinfoil in which the temperature decreased by 9 degrees