Free IB Maths AA SL lesson: Right-angle trig (SOH CAH TOA)
A ready-to-teach IB Maths AA SL lesson on Right-angle trig (SOH CAH TOA) (Unit 3 · Geometry & Trigonometry): editable slides and teacher notes, free; a printable worksheet in 2 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, 23 marks: 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
- SOHCAHTOA, Elevation/Depression & Bearings
- Pythagoras & Trig in 3D
- Choosing the Rule
- Bearings & Navigation
- Multi-Step Problems
- Given One Trig Ratio, Find the Others
- The Ambiguous Case in Context
Key vocabulary
- hypotenuse: The side opposite the right angle.
- opposite: The side across from the angle being used.
- adjacent: The side next to the angle being used (not the hypotenuse).
- angle of elevation: The angle up from the horizontal to an object.
Common mistakes this lesson tackles
- Labelling opposite and adjacent from the wrong angle.
- Calculator in radians (or gradians) instead of degrees.
- Multiplying instead of dividing when the unknown side is in the denominator.
Lesson plan
| 0–5 min | Do now: students write down what they remember about Distance & midpoint in 3D and Inverse functions & their graphs |
| 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 2 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 AA SL Unit 3: Geometry and Right Angled Trigonometry 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 AA SL Unit 3: Geometry and Right Angled Trigonometry practice questions on ibmathrevision.com, where the free questions are open and the full bank comes with a plan.