to show you think something is a good idea or that it is right for people to do.
I think more men (should/ought to) teach in elementary school.
to show something is a bad idea or that it is not right for people to do.
Greta thins women should not drive trucks.
should/should not and ought to/ought not to express the speaker’s opinion about a situation. They are used to give advice to somebody or when you want to give your opinion about a topic or situation.
Making modals (should or ought to):
Should and ought to are modals. They do not take s in the third person singular.
She should be a lawyer.
He ought to save money.
Questions and negatives are made without do.
Should we go? No, we shouldn’t.
Ought is not often used in questions and negatives.
DIFFERENCE FOR USE
Should vs. Must
Should shows that something is a good idea.
A: I can’t under this topic.
B: You should ask someone for help.
B is giving advice, but A is not forced to follow the advice. A can still decide what to do.
Must is much stronger.
A: I don’t have a driver’s license.
B: You must get a license, then you can drive.
B is giving advice, but in this situation A is forced to follow the advice. A has no choice.
Should and Ought to vs. Had Better
You can use had better to give advice.
Had better is much stronger than should and ought to, but not as strong as must.
You should go to school tomorrow. (I think it’s a good idea for you to do this.)
You had better go to school tomorrow. (If you don’t go, something bad will happen.)
Had better also expresses more urgency than should.
You should see a doctor about your cough. (It’s a good idea.)
You had better see a doctor about your cough. (It’s serious.)
You must see a doctor about your cough. (It’s obligatory.)
Had better is often used in situations in which the speaker has authority over the hearer.
Teacher to student: If you want to pass this course, you had better finish all your assignments.
Student to teacher: If you visit my hometown, you should visit the museum.
Should vs. Could
You can also use could to express opinions or to give advice. However, could is weaker than should because it only expresses possible possibilities for action in a situation. It does not show that the speaker thinks this is a good idea.
You should see that film. (I think it is a good idea for you to see it.)
You could see that film. (It is possible for you to see that movie if you want to.)
We often use could when we want to suggest all the possibilities without saying which one we think is best.
If you want to improve your English, you could take a course, you could listen to English-speaking podcasts, you could find a conversation partner, or you could take a vacation in Europe.
Should and Ought to vs, Could, Had Better, and Must
Modals can be ranked based on strength.
should / ought to
Had better refers to the present and the future. It does not talk about the past, even though it uses had.