Primary English | Modal Verbs Lesson Prep Guide (for tutors) | Three Position Rules, Strength Scale and a 20-Item Diagnostic

2026-11-08

Tutor lesson-prep guides · Primary English

Students can say “I can swim” but write “He can swims”. This lesson locks three rules: base verb after the modal, no “to”, and the modal moves to the front in questions.

Objectives — Students can: (1) state what can, must, should and may do and write one sentence with each; (2) correct errors such as “He can swims” and “She must to go” using the three position rules; (3) choose a modal using the strength scale (must 100, should 80, may 50, might 30) and explain the choice.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Present simple order	Where the subject and verb go	He plays football.
Third person -s	When a verb takes -s	he, she, it take -s
Negatives	The job of do not and does not	I do not; she does not

02 Lesson flow (45 minutes)

Time	Stage	Tutor does	Student does
0-6 min	Diagnostic	Hand out five faulty sentences and let students judge them	Tick or cross
6-16 min	Four functions	can ability, must obligation, should advice, may possibility	One sentence each
16-28 min	Three rules	Base verb, no to, modal first in questions	Rewrite three errors
28-36 min	Strength scale	must 100, should 80, may 50, might 30	Rank four sentences
36-43 min	20-item quiz	can is 30 per cent, should 25 per cent, must 20 per cent	Self-mark
43-45 min	Exit check	Three items collected and marked	Work alone

03 Teaching script (read it out)

Scene 1: Three rules, stated once

A modal verb has three hard rules: the verb after it stays in the base form (He can swim, never swims); no “to” in between (She must go, never must to go); in questions the modal moves to the front (Can you swim?).
Those three rules cover most primary errors: in the 20-item diagnostic, 3 items fail on an added -s and most of the rest fail on an added “to” or on question order. Fix those three patterns first and marks recover at once.

Ask students: correct “He can swims”, “She must to go” and “You can swim?”, and name the rule each one broke.

Scene 2: Four functions in one classroom scene

One scene can produce all four: I can swim (ability). You must wear a helmet (obligation). You should practise daily (advice). It may rain (possibility).
The diagnostic is split can 30, should 25, must 20, may 15 and could 10 per cent, so can and should together take more than half. Drill those two first and add must and may after.

Ask students: give one sentence each with can, must and should about their weekend.

Scene 3: Quantity the strength

Put the four modals on a 0 to 100 scale: must 100, should 80, may 50, might 30.
With a scale, choosing stops being guesswork: a school rule means must, a teacher suggestion means should, a weather forecast means may or might.
Watch mustn’t: it means prohibition, not absence of obligation. For “not necessary” use do not have to and teach that contrast separately.

Ask students: rank must, should, may and might from strongest to weakest and give one situation for each.

04 Question types and worked steps

Type	Example	Steps	Answer
Error correction	Fix the verb after a modal	Find the modal, then the verb	Base form, no to
Multiple choice	must, should or may	Read the clue: rule, advice, possibility	Give a reason per answer
Question form	Turn a statement into a question	Modal to the front, subject next	Question mark required
Scene sentence	Write one sentence for a scene	Fix the function first	One function per sentence

Sanity check (teach this): Sanity checks: a modal is always followed by the base verb, so He can swims is always wrong; must never takes to; questions start with the modal, as in Can you swim?; three wrong out of twenty leaves 17 correct, that is 85 per cent, not 17 per cent.

05 Independent practice (3 questions)

Question	Answer	What to watch
Five corrections	One change per sentence	Can they name the broken rule
Strength ranking	must, should, may, might from strong to weak	Is the 100 to 30 scale used
Question forms	Five statements into questions	Is the modal first
Scene sentences	A rule, a suggestion, a forecast	Do modal and function match

06 Common mistakes and what to say

Mistake	Student writes	Say this
Adding -s after a modal	He can swims.	The verb after can never changes; only can is marked for person, so leave swim alone.
Adding to after a modal	She must to go now.	Must already carries obligation; only have to takes to.
Reading mustn’t as not necessary	You mustn’t come, meaning you need not come	Mustn’t is prohibition; for not necessary write do not have to.
Question by punctuation only	You can swim?	Move can to the front so the rise in the voice has somewhere to land: Can you swim?

07 Homework (paper, section and question numbers)

Primary English chapter index — Every chapter in the subject
All prep guides — Parallel chapters
Redo this chapter — Redo items 1 to 10 and name the rule each one breaks

08 Exit check (last 5 minutes)

Question	Answer	Decision
The three position rules	Base verb, no to, modal first	Cannot say them means restart
must against should	must 100, should 80	The same means redo act three
What mustn’t means	Prohibition, not absence of obligation	Not necessary means redo act three

09 Tutor FAQ

Should can and could be taught together?

Teach can first and give could only its polite-request use, as in Could you help me?, so two meanings do not blur.

Must the strength scale be memorised?

Not the numbers, but the order must over should over may over might, so the choice can be justified.

Is must different from have to?

At primary level two points suffice: must takes no to, and have to carries to and becomes has to for he and she.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.