Science and Technology K–6 · Years 1–2

Shadow stick: tracking the sun's path across a day

Earth and Space (NSW 2017); Science understanding, Earth and space sciences, and Science as a human endeavour (ACARA v9)

Practical, model not builtLow risk

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

The sun's position changes through the day in a repeating pattern: shadows are long in the morning, shortest near midday and point the other way in the afternoon.

What you need

A broom handle held vertical in the middle of a bucket of sand so its top is 1.00 m above the flat asphalt, in full sun all day; the bucket's base width measured once
Chalk; a 5 m tape measure (a 3 m tape is too short in winter: the model gives 2.9 m at 9 am and 3.1 m at 3 pm on 21 June in Sydney); a compass or the school map's north arrow
A recording table: clock time, shadow length (cm), direction the shadow points (N, NE, E and so on); readings at 9 am, 10 am, 11 am, 12 noon, 1 pm, 2 pm, 3 pm

How to do it

At 9 am chalk the tip of the shadow and write the time beside it. The point directly below the top of the stick is inside the bucket, so measure from the tip straight to the foot of the bucket and add half the bucket's base width; that is the shadow's length. Record its direction. If the tip falls on the bucket or in the bucket's own shadow, record on the bucket.
Repeat every hour until 3 pm without moving the stick.
Join the chalk marks into a curve. Predict where the 4 pm mark would fall.
Draw a bar for each hour's length and circle the shortest.
Repeat the noon reading one month later and compare the length.

What you should see

Shadows are longest at the first and last readings and shortest close to solar noon (in Sydney about 12 noon standard time, about 1 pm in daylight saving time), and they swing from the west side in the morning to the east side in the afternoon. For most of the school day they lean south because the sun crosses the northern sky, but near the start and end of a summer day the sun is south of east or west: on 21 December the model puts the sun due east 3.3 solar hours before noon, so a 9 am daylight-saving reading (about 8 am solar time) points slightly north of west. Computed for Sydney (latitude 33.87 degrees south) with the solar model: on 21 June the 1.00 m stick's noon shadow is 1.56 m (sun 32.7 degrees up) and 2.05 m two solar hours either side of noon; on 21 December the noon shadow is only 0.18 m (sun 79.6 degrees up), short enough to fall on the bucket or in the bucket's own shadow, so near midday in December and January those readings may be recorded as on the bucket; on 21 March it is 0.66 m and on 23 September 0.65 m. On 21 June the 9 am and 3 pm standard-time shadows are about 2.9 m and 3.1 m (computed with the model, taking Sydney's solar noon as about 11.57 am standard time from the PVEducation equation of time and longitude 151.21 degrees east), so the tape must be longer than 3 m. Readings on or near those dates in Sydney can be compared with these figures; further south the noon shadows are longer. The learner knows it worked when the shortest measured chalk mark is the one nearest solar noon and the morning and afternoon marks lie on opposite sides of it.

What changes

What you change: clock time (hour by hour); date (repeat a month later)
What you measure: shadow length (cm) and direction
What you keep the same: same stick, upright, not moved
same flat surface
same measuring tape

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

The sun moves across the sky because it is travelling around the Earth (the Earth turns).
Shadows are shortest at 12 by the clock everywhere (solar noon depends on longitude and daylight saving).
In Sydney the midday sun is in the south (it is in the north all year).

Safety card

Low riskLearners carry it out

Hazards

Sun exposure across a day of readings; never look at the sun

Controls

Hats and sunscreen; readings take two minutes each; shadows, not the sun, are observed

Note

No chemicals or heat. Record the activity on the school's risk assessment (Primary School RiskAssess, Ecosolve Australia, riskassess.com.au).

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science and Technology K-6 Syllabus (2017), NESA. Current syllabus; NESA's timeline is 2026 plan and prepare, 2027 start teaching the 2024 syllabus. Code read from the official syllabus document on 2026-09-22.ST1-10ES-S ST1-1WS-S
Science and Technology K-6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST1-SCI-01 ST1-PQU-01 ST1-DAT-01
Australian Curriculum v9AC9S2U01AC9S2H01AC9S2I01AC9S2I02AC9S2I03AC9S2I04AC9S2I05

Sources

The pages the author read to write this activity.

All Concept Studio activities