Final answer:
To assess the client's understanding of the preoperative teaching, the nurse can listen to the client's statements. Understanding statements would reflect knowledge of the purpose of the colostomy and care for the perineal wound.
Step-by-step explanation:
The nurse is providing preoperative teaching for a client with colorectal cancer who will undergo placement of a colostomy with a perineal wound. The client's understanding of the teaching can be determined by assessing their statements. An example of an understanding statement would be if the client explains the purpose of the colostomy and the care needed for the perineal wound.