Comparing Right Angles

Overview

Students build on the previous lesson by identifying angles as turns and now comparing them to a right angle in everyday settings. They will use protractors to measure and sort angles as smaller than, the same as, or greater than a right angle.

Learning intentions

• Students will compare angles in everyday objects to a right angle.
• Students will measure angles using a protractor and describe what they notice.
• Students will use “quarter turn” and “right angle” language to support comparisons.
• Students will explain their thinking using clear mathematical language.

Success criteria

• I can identify a right angle in corners around the classroom.
• I can measure an angle and decide if it is smaller than, the same as, or greater than a right angle.
• I can link a quarter turn to a right angle, and explain how other turns compare.
• I can record my measurements accurately and justify my classification.

Curriculum links

• Mathematics — Measurement: identify angles as measures of turn and compare angles with right angles in everyday situations - Measurement emphasis: comparing quarter, half and three-quarter turns to right angles using protractors in context ## Lesson structure (40 minutes)

1. 0–5 min · Starter: Quick recall and hook. Teacher holds up a “right angle corner” card (two perpendicular arms) and a few quick angle pictures from the last lesson; students show with fingers whether each looks like a right angle, smaller, or bigger, then justify with a partner using turn language.

2. 5–12 min · Demonstration: Protractor skills recap. Teacher models how to place the protractor centre on the vertex, align the baseline with one arm of the angle, and read the scale at the second arm; students watch, then practise with one guided angle at their desks (teacher checks seating-to-protractor positioning).

3. 12–24 min · Stations: Measure and sort. Students rotate through 3 short stations (teacher assigns groups, 4 minutes each, plus 1 minute transition time):

• Station A (Everyday corners): Students match 6 printed angle diagrams cut from windows/books/table corners to “smaller/same/greater than” right angle, then measure 2 angles with a protractor to confirm.
• Station B (Turn cards): Students sort turn cards labelled quarter, half, three-quarter into the same categories and measure the drawn angles to verify (quarter should match right angle).
• Station C (Door opening / partial turns): Students use a simple “door hinge” diagram (or angle wheel) to create angles (small/medium/large) and measure each to compare with a right angle. Teacher circulates using a checklist: correct protractor placement, correct reading, and correct classification.

4. 24–32 min · Whole-class discussion: Compare and explain. Teacher selects 3 student examples (one smaller, one equal, one greater). Students hold up their angle measurement and explain the comparison: “My angle is greater than a right angle because…” Teacher prompts: “Which turn is closest? Quarter, half, or three-quarter?”

5. 32–39 min · Consolidation: Accuracy and reasoning task. Students complete a short worksheet (or think board-style recording) with 6 angles: for each, measure the angle, write the comparison sentence, and draw one extra right angle for reference if needed. Sentence starters are provided:

• “This angle is ___ than a right angle.”
• “It is about ___ degrees.”
• “A quarter turn is the same as a right angle, so…”

6. 39–40 min · Exit ticket. Students answer one prompt on a half-page slip: “Draw and label one angle that is smaller than a right angle, then write how you know.” Teacher collects immediately.

Resources

• Protractors (one per student)
• Angle cards/printed diagrams for stations (at least 18 total)
• “Right angle corner” model card or poster (perpendicular arms)
• Worksheet or recording sheet with measurement boxes
• Pencil, ruler, eraser
• Simple “hinge/door opening” diagrams or an angle wheel template
• Timer for station rotation
• Teacher checklist for measurement/classification

Assessment

• Formative during stations: observe protractor placement, measuring accuracy (where the baseline starts), and whether students classify correctly.
• Targeted questioning in discussion: “How do you know it’s the same as (or greater/smaller than) a right angle?”
• Exit ticket: checks ability to create an angle smaller than a right angle and justify using comparison language.

Differentiation

• Support:
• Provide sentence starters for comparisons (“smaller than / the same as / greater than”).
• Offer a “protractor tip strip” showing correct placement (centre on vertex, baseline on one arm, read at the other arm).
• For some students, reduce the number of measured angles (e.g., measure 2 instead of 3 at a station).
• Extension:
• Challenge students to find a real-life example (photo or draw) that matches each category: smaller, same, greater than a right angle, and include their measured degree value.
• EAL/SEN considerations:
• Use visual cues (right-angle marker) and consistent gestures for “smaller/same/greater”.
• Keep language anchored to turns: quarter turn (right angle), half turn (2 right angles), three-quarter turn (3 right angles).
• Classroom management:
• Use clear station roles (measurer/recorder/timekeeper) to ensure every student participates with the protractor.