Each group will time the balloon's ascent and record the time. Compare the actual time of ascent to the hypothesis. Have students take time to compare their results to that of the other groups. Special attention should be given to the results based on the size of the balloons. As a class discuss the results, making sure to relate it to the properties of air including pressure, temperature, and volume.
Students can determine the radius, diameter and circumference of the opening of the balloon.
Record the data. Determine the radius, diameter and circumference of the balloon at its widest point. Record the data. Share with class. Make an approximate calculation for the volume of the hot air balloon.