A science class has been assigned the task of developing a simple solar oven using a cardboard box as the base. The solar oven should be able to melt cheese for nachos, and the temperature should reach at least 140 °F. The total cost of the materials used must be less than $10 and the size of the oven must be 24” x 24” or less. The required temperature must be met within 60 minutes. The final outcome of the class project should be that the oven uses solar energy to make a plate of nachos, reaching the minimum temperature in the required amount of time.

The class used this design for its solar oven.
Students notice that the solar oven is not meeting the temperature requirement. One group of students suggests adding a clear plastic cover over the cooking area. Another group suggests covering the outside of the box with silver tape, especially around the corners of the box.

Suggest one more improvement that could help the design meet the temperature criterion and explain your reasoning.