Math lesson plan · 5th grade (Year 6 in England) · 45 minutes
Missing angles on a straight line and around a point
Geometry
CCSS 7.G.B.5England: Y5 GeometryEngland: Y6 Geometry
Objective and success criteria
Students will: Missing angles on a straight line and around a point.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Add and subtract angles that share a vertex
Leads to: Vertically opposite angles; Angles in a quadrilateral add to 360°
Materials: Rulers and protractors, Squared or dotted paper, Shape cut-outs, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Add and subtract angles that share a vertex). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Angle ABD is 71° and angle DBC is 66°. They sit side by side to make angle ABC. What is angle ABC? → 137Prompt: The whole angle is made of the two parts.
- Angle PQR is 120°. Ray QS splits it into two angles. Angle PQS is 11°. What is angle SQR? → 109Prompt: The two parts add up to the whole angle.
- A fan is opened so that 4 equal sections of 25° sit side by side. What angle does the open fan make? → 100Prompt: The angles join without gaps or overlaps.
Hook · 5 min
- Show a photo of a building, a tile pattern or a road sign and ask what shapes and angles students can spot.
- Share the objective: Missing angles on a straight line and around a point. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Four angles meet at a point: 101°, 58°, 94° and x. Find x.
- Step 1: 101 + 58 + 94 = 253
- Step 2: 360 − 253 = 107
- Step 3: x = 107°
- Answer: 107
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Four angles meet at a point: 57°, 65°, 182° and x. Find x. → 56Prompt: Angles around a point add up to 360°.
- On a straight line there are three angles: 90°, x and x (the two x angles are equal). Find x. → 45Prompt: Angles on a straight line add up to 180°.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Three angles sit on a straight line: 45°, 44° and y. Find y. → 91Prompt: A straight line is half a turn.
- On a straight line there are three angles: 94°, x and x (the two x angles are equal). Find x. → 43Prompt: Angles on a straight line add up to 180°.
Watch out for
- Thinking a square turned on its corner is no longer a square.
- Reading the wrong scale on a protractor.
Support and stretch
Support
- Review first: Add and subtract angles that share a vertex.
- Use concrete materials: rulers and protractors.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Vertically opposite angles; Angles in a quadrilateral add to 360°.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-5.
Free lesson plan from eurekami.com/lesson-plan-builder