A No-Prep Sub Plan for Quadratic Equations (Scotland, SQA National 5 & Higher)

A cover teacher walking into your S4 maths class at nine o'clock may be a PE teacher with a free period. Quadratic equations is a topic where that goes badly by default, because the moment a pupil asks why the formula has a plus and a minus, an adult who cannot answer loses the room. A cover lesson on quadratics has to be built so that nobody needs to explain anything. That is achievable, and the work that comes back is genuinely useful to you.

What the cover teacher is actually able to do

Assume the person in front of your class can read instructions aloud, keep time and insist on silence. Assume they cannot factorise. No modelling at the board, no "explain if needed", no questions that require a mathematical judgement. The one sentence you give them for any mathematical query is: check it against the worked example on your sheet, and if it still does not work, write your question in the margin and I will answer it on Thursday.

That instruction turns every unanswerable question into data for you rather than a crisis for them. It is the most useful line on the page.

The folder, item by item

• One instruction sheet. Numbered steps, each with a clock time written on it, not a duration. "9:05 hand out sheet A" beats "5 minutes for the starter".
• Class list with a note. Who works together badly, who has an assessment arrangement, who leaves early on a Wednesday.
• Sheet A, the warm-up. Expanding brackets only. No quadratic solving. Pupils can all start, and the room settles.
• Sheet B, the main task. A fully worked example at the top, then graded questions below it.
• Sheet C, the extension. Kept in the folder, handed out only to pupils who finish, which prevents the cover teacher having to invent anything.
• A named tray or envelope for everything to go into at the end.

Sheet B is the item that determines whether the hour works, and it needs a worked example that is genuinely complete rather than a summary of the method. Algebra – Quadratic Equations and Complex Solutions | Advanced Problem Solving Workbook | GRADE 8–11 is built that way, with the answer keys included so that a cover teacher can confirm a result without doing the mathematics, which is the difference between a calm room and a stalled one.

The hour, minute by minute

Ten minutes on sheet A, silent, which gives the cover teacher an easy win on behaviour before anything difficult happens. Twenty-five minutes on sheet B, silent for the first fifteen, then pupils may compare answers in pairs for the last ten. That switch is written on the instruction sheet as a timed event, so the noise level is a scheduled change rather than a loss of control.

Ten minutes on a self-check: answers to sheet B are in a sealed envelope marked with the time it may be opened, and pupils mark in a different colour. Five minutes at the end for the exit slip, which is one line: write the question number where you first got stuck, and what you tried. Warm-up material that a non-specialist can run without a hitch matters here, and Algebra Basics – Daily Warm-up Exercises for Expressions & Variables | Math Starter Resource | GRADE 5–9 is a good source of sheet A material precisely because it demands nothing of the adult in the room.

Reading the pile when you get back

You are looking for three things and it takes about eight minutes for a class of thirty. First, the exit slips sorted by question number, which gives you the exact point in the graded sequence where your class falls over. Second, the margin questions, which are the misconceptions in the pupils' own words and are worth more than anything you would have gathered by teaching the lesson yourself. Third, the self-marking: a pupil who has marked a wrong answer correct has a specific problem worth a two-minute conversation.

For pupils whose exit slip shows they stalled before the quadratic content, the gap is nearly always in rearranging and solving linear equations rather than in quadratics at all. Algebra – Equations and Inequalities | Foundations Workbook for Problem Solving | GRADE 5–9 gives you something to hand those three or four pupils immediately rather than reteaching the whole class.

Making it reusable

Build the folder once, in October, and leave a copy in the department office with the date of last use pencilled on the front. Rotate two versions so a class that has had it does not meet it again. Print rather than rely on a login. Come back on Thursday to a tray of marked sheets, a stack of exit slips sorted into a diagnosis, and a class that did an hour of real quadratics with someone who has never solved one.

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