Science and Technology K–6 · Years 1–2

Moon diary: recording the moon's shape for a month

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 moon's lit shape changes in a cycle of about a month, growing from new to full and shrinking back.

Safety card

Low riskAn adult supervises

Hazards

Evening observation outdoors

Controls

Done with a family adult from a garden or window

Note

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

What you need

Two 30-day diary sheets (about two months) with a blank circle for each date
A family observation task: look for the moon each evening (or in the morning sky when it is visible then) and shade the dark part of the circle; where the moon is not in the sky at all, record that rather than writing cloud
A class moon wheel made from two card circles to show the sequence of shapes
A ball and a lamp in a darkened room for the model

How to do it

Each day shade the diary circle to match the moon seen the evening before. If there was no moon to draw, write which of the two it was: not seen, cloud; or not seen, clear sky, which is what happens around new moon, when the moon is too close to the sun to be seen at all, and through the second half of the cycle, when it rises late and is a morning object.
After two weeks lay the sheets in date order and describe how the lit part changed.
Model it: one learner at a time holds the ball at arm's length, looks at it and turns slowly on the spot with the lamp as the sun, naming the shape the lit part shows at each quarter turn. Everyone has a turn, because only the holder, whose head stands for Earth, sees the phases; classmates standing around the room see the ball from other angles.
Predict the shape one week ahead from the diary and check it.
Count the days from one full moon to the next. Full moons are 29 or 30 days apart, so a single 30-day sheet usually cannot hold two of them; the two sheets always can. If cloud hides a full moon, use the shapes on the nights either side.

What you should see

The lit part grows night by night from a thin crescent to a half (first quarter, about a week after new), to full about two weeks after new, then shrinks through the last quarter back to new; the whole cycle averages 29.5 days as the US Naval Observatory states, so the count from full moon to full moon is 29 or 30 days. In the Southern Hemisphere the lit edge of a waxing moon is on the left. The ball-and-lamp model gives the same sequence in one turn. Around new moon the diary carries a run of nights with nothing to draw on a clear sky, and the simulation's model shows why: its lit fraction is zero there, so that gap belongs to the moon and not to the weather. The learner knows it worked when the predicted shape a week ahead matches what is seen, and the nights with no moon are written down as no moon rather than as cloud.

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 moon's shape changes because Earth's shadow covers it (that is an eclipse; phases come from the sun lighting half the moon and our viewing angle).
The moon only comes out at night.
A night with no moon in the diary means it was cloudy (around new moon there is no moon in the evening sky to see).

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-DAT-01
Australian Curriculum v9AC9S2U01AC9S2H01AC9S2I01AC9S2I03AC9S2I04AC9S2I05

Sources

The pages the author read to write this activity.

All Concept Studio activities