Mathematics K–6 · Years 3–4
Grid references: a map of the playground
Measurement and space
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The idea
A grid names every cell by a column letter and a row number, so a place on a map can be given and found by two symbols.
Safety card
Hazards
- moving around the playground
- trundle wheel on uneven ground
Controls
- stay inside the marked area; walk with the trundle wheel
Note
No chemicals or heat are used, so the NSW Department of Education Chemical Safety in Schools package is not needed; ordinary classroom supervision under the school's usual risk management.
What you need
- a printed map of the school grounds with north at the top and a grid of columns A to H running west to east and rows 1 to 6 numbered from the southern edge northwards
- a trundle wheel
- 10 numbered markers (cones or laminated cards)
- a compass or the map's north arrow
How to do it
- Place ten markers around the playground, with markers 1 and 2 in the same row of the map and each at the middle of its cell. For each marker, write its grid reference on the map, column letter first, then row number.
- Swap lists with another pair and find each other's markers from the references alone. Note any that were written row first and what went wrong.
- Measure the distance between markers 1 and 2 with the trundle wheel, then count the cells from the middle of one marker's cell to the middle of the other's on the map to find how many metres one cell stands for.
- Write a route from marker 3 to marker 7 using compass directions and cell counts (for example north 2 cells, east 3 cells). A partner walks it.
- Give the reference of the classroom, the office and the gate from the map.
What you should see
Every marker has one reference and every reference points to one cell; a reference written row first (3C instead of C3) sends the finder to the wrong cell, which the pair sees on the map. If markers 1 and 2 are 4 cells apart along their row and measure 40 m on the trundle wheel, one cell stands for 10 m; markers in different rows, or away from the middle of their cells, would give only a rough value, because a marker can sit anywhere in its cell. A route of north 2 and east 3 from C2 ends at F4, so if marker 7 was placed in F4 the walker finds it there.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- The order of the letter and number in a grid reference does not matter.
- A grid reference names a point, not a whole cell.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
Sources
The pages the author read to write this activity.