Science and Technology K–6 · Year 6

Walking the solar system: a scale model on the school grounds

Science understanding: Earth and space sciences

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 planets orbit the Sun at vast and very unequal distances, and a planet farther out takes longer to complete one orbit, which a model built at one scale for both distance and size makes visible.

What you need

a straight path at least 230 m long (a fence line, oval edge or footpath)
a trundle wheel or a 30 m tape measure
9 labelled stakes or cones
a ball about 7 cm across for the Sun (a tennis ball is 6.7 cm)
card, a sharp pencil and small beads to make the planets at scale size
the NASA planetary fact sheet table, printed
a calculator

How to do it

Use the scale 1 m = 20 million km. Divide each planet's distance from the Sun (in millions of km, from the fact sheet) by 20 to get metres, and each diameter in km by 20,000 to get millimetres.
Put the Sun ball at the start. Walk the distances with the trundle wheel and place a stake for each planet.
Make each planet at its scale size on a card and fix it to its stake.
Stand at Earth's stake and look back at the Sun ball. Describe how large it looks.
Copy each planet's orbital period from the fact sheet and graph period against distance.
Test Kepler's rule, found from Tycho Brahe's years of measurements: period in years = (distance in astronomical units) to the power 1.5, where 1 astronomical unit is Earth's 149.6 million km. Compare with the fact sheet.

What you should see

Mercury 2.9 m, Venus 5.4 m, Earth 7.5 m and Mars 11.4 m crowd near the Sun; Jupiter stands at 38.9 m, Saturn 71.6 m, Uranus 143.4 m and Neptune 225.8 m, 30 times as far as Earth. At this scale Earth is a 0.64 mm speck and Jupiter 7.1 mm, while the Sun is 7.0 cm, so from Earth's stake the ball looks about the size the real Sun looks (7 cm at 7.5 m spans 0.53 degrees). Kepler's rule gives Mars 1.88 years (687 days; fact sheet 687.0) and Jupiter 11.87 years (4,336 days; fact sheet 4,331), and the class graph curves upward: the outer planets are slower as well as farther.

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 planets are evenly spaced, as in most posters.
The planets line up in a row.
All the planets take a year to go round the Sun.

Safety card

Low riskLearners carry it out

Hazards

walking on a long route outside the classroom
sun exposure

Controls

route checked for traffic and hazards
adult at the far end
hats and sunscreen
small beads kept away from very young children

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

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), current, taught until 2026; code read from the syllabus document on 22 September 2026ST3-10ES-S ST3-1WS-S
Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST3-DAT-01
Australian Curriculum v9AC9S6U02AC9S6H01AC9S6I04

Sources

The pages the author read to write this activity.

All Concept Studio activities