FREE ACTIVITIES · UPPER PRIMARY AND LOWER SECONDARY
Three activities to understand the Solar System
A spectacular image sparks curiosity; a hands-on activity helps build understanding. These three activities turn sizes, distances and the classification of worlds into practical classroom problems.
ACTIVITY 01 · COMPARE DIAMETERS · 25 MIN
How many Earths fit inside each world?
Objective: distinguish diameter, surface area and volume, then understand why Solar System illustrations almost always enlarge the smaller planets.
Materials
A sheet of paper for each group, a ruler, compasses or circular objects, and the 3D atlas Size mode.
Instructions
- Choose a disc 1 cm in diameter to represent Earth.
- Ask students to estimate Jupiter's diameter before showing the comparison.
- Draw Mercury at 0.38 cm, Mars at 0.53 cm, Neptune at 3.86 cm and Jupiter at 10.97 cm.
- Compare the drawings with Size mode and explain why volume does not increase at the same rate as diameter.
ACTIVITY 02 · MAKE SPACE VISIBLE · 30–40 MIN
Build a Sun-to-Pluto distance line
Objective: understand the astronomical unit and appreciate the empty space between orbits. This activity needs a corridor, playground or other space about 40 metres long.
The scale rule
Place the Sun at zero. In this model, 1 metre represents 1 astronomical unit: the average Earth–Sun distance, about 150 million kilometres.
Mercury
0,39 m
Venus
0,72 m
Earth
1 m
Mars
1,52 m
Jupiter
5,20 m
Saturn
9.58 m
Uranus
19,2 m
Neptune
30,1 m
Pluto
39,5 m
Questions to ask
- Why are the four inner planets grouped within the first two metres?
- Which gap between markers is the largest?
- Can we draw both diameters and distances at the same scale?
ACTIVITY 03 · SCIENTIFIC DISCUSSION · 30 MIN
Why is Pluto a dwarf planet?
Objective: show that scientific classifications use explicit criteria that can be debated and revised as new discoveries are made.
Starting point
Present three statements without giving the answer: Pluto orbits the Sun; Pluto is nearly round; Pluto shares its orbital region with many other icy objects. Ask groups whether this is enough to call it a planet.
The three criteria adopted by the International Astronomical Union in 2006
- A planet orbits the Sun.
- Its gravity gives it a nearly spherical shape.
- It has cleared the neighbourhood around its orbit, meaning it is gravitationally dominant there.
Pluto meets the first two criteria, but not the third. It is therefore classified as a dwarf planet. It remains a complex world with mountains, glaciers and five known moons.
SCIENTIFIC SOURCES