If possible, provide metal Slinkies. Ask the students to treat them gently because they can knot or fasten together. Find a space for each group to stretch the Slinky. Remember that the spring must be stretched in order to make waves effectively. The file card is a 3 X 5 file card with a slot (actually, two slits) wide enough for the adding machine tape. Make one copy of the Blackline Master of sine waves for each group. Make one copy of the Blackline Master of the table for each student.