The modal pair shall/should seem like they should be the easiest modal verbs to learn, so why aren’t they? Unlike most modal verbs, there are some regional and dialectical differences between shall and should. Let’s look at their uses and differences below:
You can use the word shall for orders, commands and prophecy when used in the second (you) and third person (he/she/it, they) as well as in the first person plural (we) if you are also going to be part of the command. For example:
- The Fairy Godmother to Cinderella: You shall go to the ball.
With this sentence, the Fairy Godmother is commanding Cinderella to go the ball and get the man of her dreams.
- We shall leave at 10.
This command/order is said by a speaker who is included themselves within the command they just gave.
An example of prophecy:
- A baby shall be born and bring peace and stability to the land.
These types of sentences are more common in works of fiction that predict something to happen in the (then) future.
Questions (advice or suggestions) + shall/should
Both shall and should can also be used to ask for advice or to make a suggestion to someone. For example:
- Shall we go for lunch?
- Should we go for lunch?
Both of these sentences are suggestions although they are in question form. They would be asked by someone (potentially in an office setting between colleagues) who is suggesting that they take their lunch break.
Is there any difference between those sentences? There is no difference in meaning but there may be a difference in where you would use them. The US rarely uses the word shall, so almost all cases where shall is the default in other dialects would be replaced with should. Therefore the second sentence would be more common in the US. In other countries shall is still used (although dying out in some places) so you may be more likely to encounter the first sentence instead of the second sentence.
Normal/recommended behaviour (without strong obligation) + shall/should
You can use shall and should to show normal or recommended behaviour. It can also be used for what is done without the meaning of obligation that the word must has. For example, one could say:
- You should never lie.
- Children should be seen, not heard.
In both of these cases, the behaviour is recommended but people are not forced to follow it. This is similar to the semi-modal verb ought to.
Express the future
For more information on how shall and should express the future, please read my post on the will vs going to vs shall/should future.
You can also use should for the conditional form of shall in both conditional tenses and conditional sentences. You can find more information on how to use it in place of the modal would in conditional sentences here: A review of conditional sentences
As with the verb must, when you say shall not or should not, you are not making the act of ordering, questioning or recommending behaviour negative. Rather you are making the thing that you are ordering, questioning or recommending negative. For example:
- You should eat healthier. – a recommendation to have a healthier diet
- You should not eat junk food. – a recommendation to remove that food from your diet
Note: these sentences are not opposites! Although one uses should and the other uses should not, they are recommending (in essence)the same thing.
Want to learn more about modal verbs? Here is a guide to all the modal verbs here: introduction to modal verbs. You can also learn more about other English language information on my English Language Materials page.