Reach for the Star

Constructions and loci

Pearson Edexcel GCSE Mathematics 1MA1 · Foundation and Higher · L028 · Review v0.9

Your learning journey

Use ruler and compass constructions and interpret loci as sets of points satisfying distance conditions.

Follow the task-specific calculator guidance in Apply. Keyboard - means the same as −. Attempt before opening a scaffold or intentional practice explanation.

Answers save in this browser where storage is permitted. They do not sync. Export a backup before closing, moving or renaming this file. Avoid personal information.

Ready.

Connect & Check

Locus: set of all points satisfying a condition. Bisect: divide into two equal parts. Perpendicular bisector: line at 90° through a segment midpoint. Construction arcs: retained compass evidence.

Intentional practice feedback after your attempt

90°.

Right angle.

Intentional practice feedback after your attempt

4 cm.

Midpoint distance.

Intentional practice feedback after your attempt

Equal distances to the two points.

The common distance may vary.

Share

In pairs, predict the first step and compare your reasons before reading the worked solution: D1 Model: draw AB=6 cm; equal arcs of radius greater than 3 cm intersect above and below. Join intersections. Now construct the perpendicular bisector of AB=8 cm.

Present

Equal-radius arcs from endpoints intersect at points equally distant from both endpoints; their joining line is the perpendicular bisector. To bisect an angle, mark equal distances along its rays, then intersect equal-radius arcs from those marks. Congruent triangles explain the equal angles. Distance from a point to a line is measured along a perpendicular.

Use a sharp pencil, straightedge and compass; leave arcs visible. For a perpendicular from a point, an arc centred there cuts the line twice; bisect that segment and join to the point. At a point on a line, mark equal distances either side, then use equal arcs. For loci, draw each condition separately and retain their intersection.

Constructions and loci teaching diagram; not to scaleABMidpointPerpendicular bisectorEqual distance from A and BConstruct with arcs;leave the arcs visible.Teaching sketch • not to scale
Teaching sketch: not to scale. Use the separate practical sheet for drawing tasks. Describe your reasoning here; your teacher reviews the paper drawing.
Optional scaffold

Choose radius greater than 4 cm.

Intentional practice feedback after your attempt

Line through midpoint at 4 cm, perpendicular to AB, with intersecting arcs.

Equal-distance intersections determine the bisector.

Optional scaffold

Keep compass opening equal for paired arcs.

Intentional practice feedback after your attempt

Two 35° angles; construction arcs retained.

Protractor makes the starting angle, not the bisector.

Optional scaffold

A fixed distance is the radius.

Intentional practice feedback after your attempt

Circle centre P, radius 3 cm.

Only circumference; no interior shading.

Optional scaffold

Consider both sides of the line.

Intentional practice feedback after your attempt

Strip between parallel lines 1 cm each side, including boundaries.

Distance measured perpendicular.

Apply

Optional scaffold

Choose a radius reaching across l.

Intentional practice feedback after your attempt

Arc from P cuts l at X,Y; bisect XY and draw through P to l.

The constructed line is at 90°.

Intentional practice feedback after your attempt

Two intersections of radius-4 circles centred A and B.

Both conditions must hold.

Intentional practice feedback after your attempt

Intersect the closed radius-3 disc with the perpendicular bisector of AB.

May be a segment, point or empty, depending on positions.

No calculator needed. Practical construction quality is teacher reviewed. Use a ruler to check distances and a protractor to check right angles after constructing; they do not replace compass evidence.

Apply and extend

Intentional practice feedback after your attempt

One equidistant point is insufficient to locate the bisector line; use two intersections, or one and the known midpoint. Joining A is generally wrong.

A is not equidistant from itself and B.

Intentional practice feedback after your attempt

None; the two circles are separated since 3+3<8.

Maximum total reach is 6 cm.

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

Coordinates record horizontal then vertical displacement. A translation moves every point by the same vector. Reflection preserves perpendicular distance to its mirror line.

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

Original Reach for the Star. Not an official or endorsed Pearson resource. Separate teacher package contains assessment solutions. Local saving is browser-dependent; no account or dashboard service is included.

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

4 cm; every point on the bisector is equidistant from endpoints.

Deep challenge

Reveal a worked check after attempting

Intersections of circles centred A radius 3 cm and B radius 4 cm, if the circles meet; up to two points.

Recall & Review: feedback and extension integration

Lesson L028: Constructions and loci

Objective: Use ruler and compass constructions and interpret loci as sets of points satisfying distance conditions.

60-minute structure: 0-7 Connect & Check; 7-14 Share; 14-25 Present/model; 25-44 Apply route choice/practice; 44-52 independent exam-style check; 52-60 Recall & Review, WWW/EBI and next step.

What Went Well (WWW)

I selected the correct geometric fact, theorem, formula or transformation and used a clear diagram with appropriate labels and units.

Even Better If (EBI)

I will name the fact or theorem, show the substitution or construction step and check whether the size, direction and units of the result are reasonable.

Stretch and deep challenge

Stretch: Construct the perpendicular bisector of an 8 cm segment. How far is its midpoint from either endpoint?

Deep challenge: A point is 3 cm from A and 4 cm from B. Describe the intersection of its loci.