Encourage the students to contrast transverse and compressional waves. Try to get the students to think in terms of how the direction of the back-and-forth motion compares to the direction of motion of the wave as a whole (in a compressional wave, the directions are the same; in a transverse wave, they are perpendicular).

When the students do Step 2 of For You To Do, point out that the spring is moving from side-to-side, but the pulse is moving along the spring. In Steps 3 and 4, encourage them to make a sharp, well-defined pulse, which they can time more accurately than a broad pulse. In Steps 8 and 9, you may have to help the students choose a time interval and then convert the measurement of cycles in that interval into cycles in one second (to get the frequency). In Step 13, ask the students to be gentle with the wave viewers. Suggest that they pull the paper tape through slowly enough so they can observe the motion through the slit.
Try to keep the groups as well-separated as possible.

Safety Precaution: Students must keep a firm grip on each end of the spring.