Free IB Maths AI SL lesson: Parallel & perpendicular lines
A ready-to-teach IB Maths AI SL lesson on Parallel & perpendicular lines (Unit 2 · Functions): editable slides and teacher notes, free; a printable worksheet in 3 levels with answers for school plans. About 55 minutes.
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What's inside
- Slides (PowerPoint, editable) · freeabout 12 slides: do now, objectives, key ideas, a worked example step by step, “your turn”, practice QR code, exit ticket
- Teacher notes (PDF) · freelesson plan with timings, common mistakes, homework links
- Worksheet (PDF) · school plans4 questions, 20 marks: Fluency, Reasoning, Exam-style. Included with school plans and the teacher trial.
- Answers (PDF) · school plansthe answer to every worksheet question, from its mark scheme. Included with school plans and the teacher trial.
Learning objectives
- Parallel and perpendicular lines
Key vocabulary
- parallel: Lines with the same gradient that never meet.
- perpendicular: At right angles; the gradients multiply to −1.
- negative reciprocal: −1/m: flip the gradient and change its sign.
- perpendicular bisector: The line that cuts a segment in half at right angles.
Common mistakes this lesson tackles
- Voronoi diagrams and bisectors: midpoint, negative reciprocal, vertices. Perpendicular bisector: midpoint of the two sites, gradient −1/m, then y − y₁ = m(x − x₁). A vertex is where two bisectors meet: solve them together. Vertical and horizontal bisectors are x = … and y = ….
- Using 1/m or −m instead of −1/m for a perpendicular gradient.
- Using the gradient of the original line through the midpoint for a perpendicular bisector.
Lesson plan
| 0–5 min | Do now: students write down what they remember about Straight-line graphs (m and c) and Logarithms & exponential equations |
| 5–8 min | Share the learning objective and success criteria |
| 8–20 min | Teach: the worked example, step by step; students copy the method |
| 20–25 min | Your turn: 1 mini-whiteboard question; check every board before moving on |
| 25–42 min | Practise: the worksheet (4 questions in 3 levels, with school plans and the teacher trial) or the topic's practice questions online; move up a level after two right in a row |
| 42–47 min | Plenary: 1-question exit ticket; collect it to plan the next lesson |
For students: practise this topic
The worksheet's QR code opens the IB Maths AI SL Unit 2: Coordinate Geometry practice questions.
What schools get
- Set this lesson as homework, marked by AI against the mark scheme, with every result in your markbook (school Pro plan).
- This lesson's worksheet in three levels, with its answers, ready to print.
- Support, Core and Stretch versions and A/B copies of the worksheet from the full question bank, in the worksheet builder.
- Create lesson: this lesson rebuilt for your class's next scheme-of-work lesson, from the full bank.
School licences from €490 a year. Try everything free for 30 days as a teacher: no card.
Questions teachers ask
Is this lesson free?
The slides and the teacher notes are free to download with a free IB Math Revision teacher account (sign in with Google, Microsoft or email); no card. The printable worksheet in three levels and its answers are included with school plans and the free 30-day teacher trial.
Can I edit the slides?
Yes. The slides are an ordinary PowerPoint file: change, add or delete anything. They also open in Google Slides and Keynote. The logo and web address sit on the slide master, so your edits do not move them.
What do students use for homework?
The practice slide's QR code and web address take students to the IB Maths AI SL Unit 2: Coordinate Geometry practice questions on ibmathrevision.com, where the free questions are open and the full bank comes with a plan.
More free IB Maths AI SL lessons
- Previous: Straight-line graphs (m and c)
- Next: Interpreting quadratic vertex + roots in context
- Same topic, IB Maths AA SL: Parallel & perpendicular lines
- All free IB Maths AI SL lessons
- IB Maths AI SL scheme of work