Your learning journey
Calculate missing angles and justify each step using named angle facts and marked parallel lines.
Follow the task-specific calculator guidance in Apply. Keyboard - means the same as −. Attempt before opening a scaffold or intentional practice explanation.
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Ready.
Connect & Check
Vertex: meeting point of rays. Transversal: line crossing two lines. Corresponding: matching position. Alternate: opposite sides of a transversal between the lines. Supplementary: sum of 180°.
Intentional practice feedback after your attempt
115.
Half-turn total.
Intentional practice feedback after your attempt
150.
Full-turn total.
Intentional practice feedback after your attempt
x=70.
Subtract 40 and divide by 2.
Present
A straight angle is half a turn, 180°; a full turn is 360°. At intersecting lines, opposite angles are equal because each supplements the same adjacent angle. With parallel lines, corresponding and alternate angles are equal; co-interior angles sum to 180°. A diagram that merely looks parallel is insufficient.
Mark known angles and parallel arrows. Identify a relationship before calculating. Write an equality or sum, solve, then check the angle type. Use the diagram sheet to trace the relevant rays.
Optional scaffold
Use a 180° total.
Intentional practice feedback after your attempt
y=107°.
180−73.
Optional scaffold
Subtract the known angles from 360°.
Intentional practice feedback after your attempt
y=155°.
360−80−125.
Optional scaffold
Distinguish opposite from next to.
Intentional practice feedback after your attempt
117°; 63°.
Opposite equal; adjacent sum 180°.
Optional scaffold
Set the alternate angles equal.
Intentional practice feedback after your attempt
x=20.
3x+10=70.
Apply
Optional scaffold
Name each pair first.
Intentional practice feedback after your attempt
48°, 48°, 132°.
Only the co-interior partner is supplementary.
Intentional practice feedback after your attempt
x=50; 120° and 60°.
3x+30=180; check sum.
Intentional practice feedback after your attempt
116°.
Adjacent angles sum 180°; corresponding angles transfer between crossings.
Non-calculator reasoning. Optional check: 95+85=180. A calculator cannot identify an angle relationship.
Apply and extend
Intentional practice feedback after your attempt
Appearance is not evidence of parallelism. Equality requires parallel lines or another given reason.
Use markings or stated information.
Intentional practice feedback after your attempt
Both equal 180−a, so they are equal.
This is a general argument, not a measurement.
Access, Scaffold, Core and Stretch support the same goal. Stretch deepens reasoning for either qualification tier.
Recall & Review
Retrieval without notes
Six retrieval points. Enter a number, decimal, fraction such as 3/2, or mixed number such as 1 1/2. Equivalent numeric values are accepted. Unsupported notation goes to teacher review. For rounding, also communicate the requested accuracy in written work; numerical scoring cannot judge significant trailing zeros.
Not checked.
Independent exit evidence
P1–P2: five minutes, no notes, 4 marks. Your teacher reviews working and explanations. Full assessment solutions are not embedded.
Recall & Review and prepare
A line through a triangle vertex parallel to the opposite side lets alternate angles transfer onto a straight line. This explains the triangle angle sum of 180°.
Retrieve F1 again in one week. Bring your working and one question.
Your progress summary
Completion records attempts, not mastery. Retrieval points describe the latest checked attempt. Your teacher reviews P1–P2 separately and checks retained understanding after a delay.
Restore a backup
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Optional extension activities
Allow 10–15 minutes if the main practice is secure. Show your method, explain a check and justify your conclusion.
Stretch
Reveal a worked check after attempting
5x+30=180, so x=30°.
Deep challenge
Reveal a worked check after attempting
Alternate angles on parallel lines are equal; co-interior angles add to 180°.