People revise models when observations do not fit. Ptolemy developed an Earth-centred model. Copernicus set out a Sun-centred planetary model. Galileo’s telescope observations supported change. They did not alone prove every part of modern astronomy. Older cultures did not all share one model. Safety: Paper-only observations; never aim an optical device at the Sun. Stop: Stop at these two observations. No telescope, solar observation, or historical role-play trial is required.

Materials: Paper; Pencil 1. Draw two boxes. In Ptolemy’s geocentric box put Earth at the centre, with Sun and planets around it. In Copernicus’s heliocentric box put the Sun centrally, Earth among the planets, and the Moon around Earth. Label both schematic, not to scale. 2. Make three timeline cards: about AD 150—Ptolemy’s developed Earth-centred account; 1543—Copernicus’s major book on Sun-centred planetary motion; 1610—Galileo’s telescope observations of Jupiter’s moons and Venus’s phases. Order the cards; equal gaps on paper do not mean equal time. 3. Write two observation cards: four points change position around Jupiter; Venus shows a full set of phases. Link the first to the claim that not everything orbits Earth. Link the second to Venus travelling around the Sun. 4. Write a two-sentence model-change report naming all three people. Add: these observations challenged Ptolemy’s arrangement, but other historical models could also place Venus around the Sun. Done: Complete two labelled models, three dated cards, and an observation-to-claim explanation. Proof: Keep the models and report. Note if names, dates, or the evidence link were copied from the reference cards. Stop: Stop at these two observations. No telescope, solar observation, or historical role-play trial is required.