The excessive standardization in teaching has sterilized students' independent thinking.

sterilized 是动词 sterilize 的过去分词形式。sterilize 由词根 sterile（无菌的、贫瘠的）加上动词后缀 -ize 构成，本义是"消毒、使无菌"，引申为"使失去活力/创造力"的意思。在句中表示"使...丧失"的被动含义。