It should lift the book. Keep adding books one at a time. Students will be amazed at how much weight the air in the bag will lift. This will give them a better understanding of how hot air balloons work. Discuss rules of the road for bicycle safety.
Students can make posters to promote the bicycle safety rules.
Use a small toy boat to dramatize the story. Float the boat in a baby's bath tub. Have students experiment with different objects to see which will sink the boat. Make a graph of which objects cause the boat to sink. Fold two of the corners over so they meet in the middle.