The Open and Close dates determine when the quiz is available. If you do not select the Enable checkbox for Open the quiz, the quiz will be permanently open, instead of becoming available on a given date. If you do not select the Enable checkbox for Close the quiz, then once the quiz is open and will stay open permanently instead of becoming unavailable on a given date.

If you want to hide a quiz, further down on this page, under Common module settings, you will see the Visible setting; change this setting to Hide.

By default, a quiz does not have a time limit. If you want to set a time limit, use the Time limit setting. When time runs out, the quiz is automatically submitted with the answers that have been filled out. A time limit can help prevent the use of reference materials while taking the quiz. For example, if you want students to answer the questions from memory but all the answers are in the course textbook, setting a timer might discourage students from taking the time to look up the answer to each question.

When students are taking a timed quiz, they see a countdown timer on the quiz page.

If you set a time limit for the quiz, in the quiz's description, inform the students about what happens when the time limit is reached. For example, if you configure the quiz to discard the student's answers if the student has not submitted the quiz in time, inform the student about this.