Each group needs:

• 1 dry sponge
• 1 plate, plastic or aluminum
• 1 plastic spoon
• a cup
• water, 1 cup
• paper and pencil, to keep a tally
• Sponge Saturation Worksheet, one per student
• Relative Humidity Graph, as a handout for each group or each student, or as an overhead projector transparency to show the class
• (optional, if students are graphing data) graph paper, one sheet per student

For the entire class to share:

• the day's humidity, such as from the newspaper weather page, television or radio weather broadcast, or Internet weather website