I often recall a lesson from one of my favorite school teachers. During vocabulary lessons of looking up the definitions of words, she reminded her students not to use the word or a form of the word in the definition. We were expected to research completely different phrases in the definitions.
This teaching technique was brought to memory when I read one of the aspects of a natural critical learning environment in What the Best College Teachers Do. This environment helps students answer the question when the teacher gets the students to answer the question for themselves (page 103). Students are challenged to develop explanations and arrive at their own conclusions, rather than simply being told the answer.
As an elementary student looking up definitions in a dictionary, I could have simply copied the definitions even though some words may have been defined in the dictionary by a form of the same root word. My teacher encouraged me to seek the definitions of words without using any forms of the root word.
Effective teachers do not give students answers; they encourage them to find their own answers and research all parts of that answer.