Which type of science project could be done to explain what relative humidity is?

A simple science project to explain relative humidity could involve using a hygrometer, which measures moisture in the air. Students can create a DIY hygrometer using a balloon, a straw, and a scale to observe how the balloon expands or contracts with changes in humidity. By measuring the changes in the balloon's size in different environments (like indoors vs. outdoors or during different weather conditions), students can visually demonstrate how relative humidity varies and its effects on everyday life. This hands-on approach helps to solidify the concept in a tangible way.