Final answer:
To ensure effective CPR, remind your classmate of the importance of allowing for complete chest recoil between compressions.
Step-by-step explanation:
If your classmate is not allowing for complete chest recoil, you should remind them the importance of proper technique during CPR. In CPR, it is essential to allow for complete chest recoil between compressions to ensure effective blood flow. Complete chest recoil allows the heart to refill with blood, maximizing the chances of restoring circulation. Failing to allow for complete chest recoil can compromise the effectiveness of CPR.