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📘 Two sentences. One extra word.

You swim. You can swim: one sentence reports an action, while the other adds ability. That extra word, can, is a modal verb — a small helper that can also signal permission, a guess, a rule, or a polite ask.

6
lessons
~30 min
to learn
Adults
level
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What you’ll learn

  1. The helper that sits in frontDefine a modal verb as a helper that sits in front of a base verb, name the main set, and apply the form rules (no -s, no to, questions flip).Modal auxiliaries do not name the action. They change what the action is allowed to mean. English leans on ten of them, and they follow a tight shape: subject + modal + base verb.
  2. Can and could, the ability pairUse can for present ability and could for past ability, and tell those jobs apart from possibility and polite asking.Can is the present skill. Could often sends that skill into the past. Both words can also soften a chance or a request, but the time of the ability is the cleanest way to choose between them.
  3. Asking at the classroom doorChoose may, might, could, or can to ask or give permission, matching the formality of the room.Permission almost always arrives as a question. May is the formal knock, can the everyday one, could the polite middle. Giving permission uses may or can, not usually might or could.
  4. How sure are you?Order might, may, should, will, and must as degrees of possibility, and recognise adverbs such as perhaps and surely as the same job.Year 5’s core skill is hearing how sure a sentence sounds. In a weather example, the helper can climb from might to must, but the scale is a useful guide rather than a rule for every sentence. Adverbs of possibility tilt the same scale.
  5. Must, should, and the hard noSeparate must (rule), should or ought to (advice), mustn’t (ban), and don’t have to (not required).A red light is must. Handwashing advice is should. A do-not-touch sign is mustn’t. Don’t have to is freedom, not a ban. Mixing those four changes the world of the sentence.
  6. Will, would, and what you noticeUse will for a confident future, would for a polite request, and a three-step check to pick any modal on purpose.Will plans or predicts. Would cushions a request. Negatives keep the helper and add not. The last skill is not a list: it is noticing a modal in the air and naming the job it is doing.

Questions this course answers

In She can swim, what job is can doing?

Can is a modal auxiliary. The main verb is swim. The modal adds the meaning of ability and stays in front of the base verb.

Choose the helper that fits the form rule.

After a subject like she, a modal still does not take -s, and it is not followed by to. The correct form is She can swim.

Match each sentence to the job the modal is doing.

The same small set of helpers covers several jobs. Can here is ability, may is permission, might is a weak possibility, and must is a strong rule.

Put these possibility helpers in order from least certain to most certain.

Year 5 asks you to show degrees of possibility. Might is a weak chance, may is an open chance, should is what you expect, and must is a strong conclusion from evidence.

I could swim when I was six. What does could mean here?

Could is often can sent backward in time. The sentence reports a skill that belonged to then, not a request or a rule.

In your own words, why is She cans swim wrong?

Ordinary verbs add -s after she: she swims. Modals never do. She can swim is the only correct shape.

Grounded in trusted sources

  • Department for Education, English Appendix 2: Vocabulary, grammar and punctuation (Year 5: modal verbs might, should, will, must; terminology: modal verb), https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/335190/English_Appendix_2_-_Vocabulary_grammar_and_punctuation.pdf
  • Department for Education, National curriculum in England: English programmes of study (upper key stage 2: using modal verbs or adverbs to indicate degrees of possibility), https://www.gov.uk/government/publications/national-curriculum-in-england-english-programmes-of-study/national-curriculum-in-england-english-programmes-of-study
  • Common Core State Standards Initiative, CCSS.ELA-Literacy.L.4.1.c: Use modal auxiliaries (e.g., can, may, must) to convey various conditions, https://www.thecorestandards.org/ELA-Literacy/L/4/
  • University of North Carolina at Chapel Hill Writing Center, Modals (functions, strength order for possibility, ability, necessity, permission), https://writingcenter.unc.edu/tips-and-tools/modals/
  • Scott McLean, Writing for Success, section 5.6 Modal Auxiliaries, via LibreTexts (ten main modals; subject + modal + main verb; common form errors), https://human.libretexts.org/Bookshelves/Composition/Introductory_Composition/Writing_for_Success_(McLean)/5%3A_Help_for_English_Language_Learners/5.6%3A_Modal_Auxiliaries
  • San José State University Writing Center, Verbs: Modals, Michael Wong, Fall 2021 (possibility scale; formality of permission; no -s and no to), https://www.sjsu.edu/writingcenter/docs/updated-handout-pdf/Verbs-%20Modals.pdf

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