A transit is a small dip in starlight when a planet crosses in front of its star from our viewpoint. A planet can also tug its star into a small wobble, measured through Doppler shifts in the star’s light. Neither method directly shows life. A habitable zone permits possible surface liquid water under suitable conditions; it does not promise water or life. Safety: Paper analysis only; do not look at a bright lamp to imitate a transit. Stop: Stop at fictional evidence. Do not announce a real discovery or search for life-detection news.

Materials: Paper; Pencil; Ruler 1. Make a graph with time 0–8 in equal steps on the horizontal axis and relative brightness 98–100 on the vertical axis. Plot these illustrative values: 100, 100, 98, 100, 100, 100, 98, 100, 100. Join successive points. These are fictional practice readings. 2. Circle the two dips, at times 2 and 6. Draw a star circle and a small planet crossing its face. Link the crossing to a dip. Write: repeated dips suggest an orbit; other causes must be checked. 3. Make a separate wobble sketch: star and planet move around a shared centre. Label star approaching—light shifted bluer; star receding—light shifted redder. No speed or colour scale is represented. 4. Write three illustrative planet cards: A—rocky, in habitable zone, atmosphere unknown; B—rocky, in habitable zone, water vapour detected; C—same as B, with substantial oxygen and methane detected together. Rank which card merits the strongest follow-up for possible life. Explain why none proves life. 5. Finish with a note: oxygen and methane can react, so their continued coexistence can suggest replenishment. Test non-living chemistry and the star’s effects too. Done: Complete the graph, two method sketches, and a qualified three-card comparison. Proof: Keep the graph and life-claim note. Record adult help plotting dips or supplying the caution. Stop: Stop at fictional evidence. Do not announce a real discovery or search for life-detection news.