Every time we speak or write, we signal how certain we are about what we are saying. 'It will rain tomorrow' is very different from 'It might rain tomorrow' or 'It could rain, I suppose'. The grammar we use to signal degrees of certainty is called hedging when we want to sound cautious, and boosting when we want to sound confident. For teachers, this matters in two directions: first, students often write as if everything they say is certain fact, which makes their writing sound overconfident and sometimes inaccurate; second, teachers themselves need hedging language for professional communication — writing to parents, producing reports, discussing assessment results. This lesson maps the full system from certain to uncertain and shows how modal verbs, adverbs of probability, and negative understatement work together.
Before you start — think honestly about your own teaching and experience.
Look at the examples. Answer each question before reading the explanation — this is how your students will learn too.
All five sentences are about the same future event. What changes between them? If you were a farmer deciding whether to harvest your crops tomorrow, which sentence would most concern you? Which would you almost ignore?
The modal verb alone signals the speaker's confidence level. 'Will' presents the rain as certain; 'should' signals expectation based on evidence; 'may' signals genuine possibility; 'might' and 'could' signal lower probability. Choosing the right modal is not just grammar — it is an honest representation of how much you know. A weather forecaster who says 'It will rain' when the data shows only a 40% chance is misleading their audience. Students who write 'The results will improve' when they mean 'The results may improve' are making the same error — claiming more certainty than they have.
These sentences use adverbs rather than modals to signal certainty. Where do these adverbs sit in the sentence? Can they be moved? What is the difference between 'certainly', 'probably', and 'arguably'?
Adverbs of probability ('certainly', 'probably', 'possibly', 'arguably', 'apparently', 'presumably') sit before the main verb or after an auxiliary: 'have certainly improved'. They can also appear at the front of the sentence for emphasis: 'Certainly, the results have improved.' 'Certainly' signals the speaker is confident; 'probably' signals high but not complete confidence; 'possibly' signals genuine uncertainty; 'arguably' is special — it signals that a claim could be made but invites disagreement. 'Arguably' is a powerful word in academic writing because it introduces a strong claim while signalling awareness that not everyone agrees. Students who do not know this range default to 'I think' for everything, which is less precise and sounds less authoritative.
These sentences all use a double negative structure. But unlike the double negatives covered in the negatives series, these are deliberate. What do they communicate? Are they stronger or weaker than the simple positive?
Deliberate double negatives using 'not + negative prefix/adjective' are a classic hedging tool in formal English. 'Not unintelligent' is weaker than 'intelligent' — it means somewhere between neutral and positive, and the speaker is deliberately not committing to the full positive. This understatement is common in formal reports, academic writing, and professional assessments. 'The results were not disappointing' is more cautious than 'The results were good' — it signals that expectations were met but does not claim more than that. Students who know only the direct positive forms miss this whole register of careful, precise communication.
| Form | Use / Meaning | Example |
|---|---|---|
| Level of certainty | Modal verbs | Adverbs |
| Certain (100%) | will, shall (formal) | certainly, definitely, undoubtedly |
| Near certain / expected | should, ought to | almost certainly, in all probability |
| Probable (>50%) | will (+ probably) | probably, likely, presumably |
| Possible (~50%) | may | possibly, perhaps, conceivably |
| Less certain (<50%) | might, could | possibly, perhaps, arguably |
| Cautious positive (understatement) | (not + negative adj.) | not without, not entirely, not altogether |
The distinction between epistemic modals (expressing certainty about truth) and deontic modals (expressing obligation or permission) is one of the most important and least-taught aspects of modal verbs. Students who know only the deontic meanings miss half the system. A practical classroom rule: if you can replace the modal with 'it is certain/possible/likely that', it is an epistemic use. If you can replace it with 'it is required/permitted/recommended', it is deontic. 'She must be tired' → 'It is certain that she is tired' ✓ epistemic. 'You must submit the form' → 'It is required that you submit the form' ✓ deontic. Both uses are common; both are important for professional communication. Also worth noting: the hedging level of a modal can shift in reported speech. 'It may rain' → 'She said it might rain' — the backshift from 'may' to 'might' makes the uncertainty seem even greater, which can unintentionally misrepresent the original speaker's confidence level.
When choosing a hedging level: • Am I certain this is true? → Use 'will' / 'certainly' / 'definitely' • Do I expect this to be true based on evidence? → Use 'should' / 'probably' / 'in all likelihood' • Is this genuinely possible but uncertain? → Use 'may' / 'possibly' / 'perhaps' • Is this only theoretically possible? → Use 'might' / 'could' / 'conceivably' • Am I cautiously acknowledging something positive without fully committing? → Use 'not + negative adjective' Checking student writing: does every claim carry the same certainty marker, regardless of the evidence? If so, the student needs to calibrate their hedging.
Choose the hedging expression that best matches the level of certainty described in brackets.
Each sentence uses hedging language incorrectly or at the wrong level. Find the problem and suggest a better version.
Use this sequence directly in class — guided discovery, no textbook needed. Tap each step to mark it done.
STEP 1 — The certainty scale (5 min): Draw a line on the board from 0% to 100%. Write 'It will rain' at 100% and ask students where they would place 'It might rain', 'It may rain', 'It should rain', 'It could rain'. Discuss. Establish that modal verbs are not interchangeable — each sits at a different point on the scale and choosing the wrong one misrepresents what you know.
STEP 2 — Epistemic vs deontic 'must' (6 min): Write two sentences: 'You must submit the report by Friday' and 'She must be tired — she has been working since dawn.' Ask: what does 'must' mean in each? Establish the two meanings: obligation (deontic) and logical deduction (epistemic). Give two more examples and ask students to decide which meaning applies.
STEP 3 — Adverbs of probability (6 min): Write a neutral sentence: 'The results have improved.' Ask students to add a different adverb of probability to each version and discuss how the meaning changes: 'certainly', 'probably', 'possibly', 'arguably'. Ask: which would you use in a school report? Which in a letter to a worried parent?
STEP 4 — Professional hedging in context (8 min): Give students three 'overconfident' sentences from imaginary school reports. Ask them to rewrite each with appropriate hedging: replace 'will' with 'should' or 'may', replace 'certainly' with 'probably', replace blunt negatives with understatement or cautious positives. Share and compare.
STEP 5 — Consolidate: write three report sentences (10 min): Ask each student to write three sentences about an imaginary student's performance — one expressing a confident assessment, one expressing a genuine uncertainty, and one using negative understatement to acknowledge a problem diplomatically. Students share one sentence each.
Use directly in class — copy, adapt, or read aloud. No printing needed.
For each strategy, choose the option that best describes where you are now.
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