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Full access Geometry and mathsArt and pattern

Parallel streets, perpendicular crossings

A grade 4 pupil uses a 3D pen to make two flat PLA tools: a right-angle corner tool and a parallel frame: checks them on the printed test pairs and with a set square, then places them on an original neighbourhood plan: checks two street pairs for parallelism and two crossings for perpendicularity, records the results in a table and draws two missing streets in pencil along the tools’ edges.

Age
9–11 years
Length
approx. 45 min
Level
Easy
Where you teach
School
Purpose
Educational
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How to run this session

Stages and timing
  1. Work area and the corner tool’s first layer
  2. Second layer on both arms and the brace
  3. Test pairs: does your corner tool hold a right angle?
  4. Frame: closed 80x60 mm outline
  5. Drawing edges and handle
  6. Cold tools: checking and clearing the work area
  7. Four street pairs
  8. Draw the two missing streets
  9. Optional: streets closer together than the frame’s sides

What gets built

The pupil recognises parallel and perpendicular segments in a drawing where the paper’s edge gives no clue: checks them with a self-made tool and explains the evidence. After the lesson, the pupil draws a parallel pair and a perpendicular pair along the tool.

What it practises
  • Making a flat PLA instrument with a specified right angle and spacing. Independently checking the instrument in three stages (pattern, test pairs, set square) before use.
  • Recognising parallel and perpendicular segments in a drawing without clues from the paper’s orientation.
  • Drawing a segment along an instrument’s edge rather than freehand.
  • Distinguishing 'looks like' from 'I checked' when judging geometric relationships.

Success criteria
  • The Lime-Maple pair is marked parallel and Lime-School perpendicular (both entries correct).
  • At least 3 of the 4 table rows agree with the teacher’s key.
  • New Street is drawn along the other long side of the frame placed on Maple, and passes through the square.
  • Short Street is drawn along the corner tool’s short arm and starts at Sunny Plaza.
  • The pupil explains the evidence that a street pair is parallel or perpendicular.

What you need
Filament
PLA
Colours
colour shown in the illustration
Also
3D pen suitable for PLA: 1 per pupil., 1.75 mm PLA filament: 1.0 m (3.0 g) per pupil (both tools), one dark, saturated colour., Pen power supply: 1 set., Work mat resistant to the working temperature of PLA: 1 item., MAT02-W1 1:1 pattern (A4): 1 sheet per pupil., W2 neighbourhood plan (A4): 1 sheet per pupil., Pencil: 1 per pupil., Set square: 1 per pupil + 2-3 spares held by the teacher.

Files

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Version 8ef43531-7f26-45a2-b4a6-fc65269c8238 Updated 2026-10-14

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