Make the function of short-answer question
I suggest the function of short-answer questions. Currently, I know that there is the function "study set", but we can pass a question despite we didn't memorize it accurately. So, it can be prohibited by make the type of question of "short-answer question".
More specific form is as below.
Form of the document is same with the study set. However, the method which it tests us will become "short-answer questions". Only if we write the accurate answer, we can pass to the next question. If we don't know about the answer, click the 'answer' button, then we can see the answer. But at this moment, we can't input the answer. Next time, we can challenge to that question.