Inflate the balloon, measure the width of the balloon, heat the balloon using the heat lamp, and then measure the width again.
Answer:
When designing an experiment, always keep in mind the question that needs to be answered.
In Juan's case, he wants to see how air expands when heated. Therefore, he will need to inflate the balloon, measure the width of the balloon, heat the balloon using the heat lamp, and then measure the width again.
Explanation: