The rule as a picture, 5 multiple-choice questions, 3 sentences to correct and a short writing task. Free to print and copy for your class or for self-study.
Want the explanation first? Read the Should vs Must lesson
Should gives advice: it's a good idea, but it's the other person's choice: You should see a doctor. Must is stronger: it's necessary: You must see a doctor immediately.
You should see a doctor about that cough.
You must see a doctor. It looks serious.
Write two sentences about your own life: one with Should and one with Must. Then explain the difference to a partner.
Answers will vary. Check that each sentence follows the rule on page 1, or paste them into Clarigram to have them checked.