A child starts to produce words when he or she is about __________ of age

Melatonin, a hormone that regulates sleep and wakefulness, is produced by the _____ gland

a) pineal b) pituitary c) parathyroid d) thymus

Because some behaviors occur rarely or in private, it can be useful to use methods other than

a. surveys. b. correlational methods. c. observational methods. d. experimental methods.