A Perfect Place to Live

Teacher Tips

Hook

• It helps to take the question “What do you need to know before deciding?” seriously and leave it open. Distance from the star, whether it needs a moon, what the mystery liquid is: leaving these unresolved is what pulls learners into the pathway.
• If a learner guesses water straight away, it helps not to confirm it. You might say something like “Hold that thought. See if you can explain why water specifically matters,” and let the pathway do the explaining.
• It’s worth keeping the reveal focused on what you don’t know yet rather than what you do. The gap is doing the work here, not the facts you’ve already given them.

ITZA Pathways

• On the Goldilocks Zone pathway, it helps to push for a specific reason Mars fails, not just “too cold”. Something like “too small to hold onto an atmosphere” is what you’re listening for, rather than only a temperature.
• On the water cards, you might check that learners can explain why ice floating matters, not just that it does. “If ice sank, oceans would freeze from the bottom up” is the version that sticks.
• On the Moon pathway, you could ask “What would Earth look like if the Moon had never formed?” It’s a good way to pull axial tilt, day length and tides into one answer instead of three separate facts.
• If someone’s gone quiet, “Which fact surprised you most?” works on either pathway to get them talking again.

Classroom Activity

• It helps to talk through the first planet as a whole class before pairs go off on their own. Showing together that it fails every criterion gives them the pattern to apply.
• After that, pairs work through the rest in a few minutes each, reaching one of three verdicts: impossible, unlikely or possible. Unlikely isn’t a soft version of impossible, so it’s worth keeping pairs from blurring the two.
• Watch for pairs who jump to “possible” the moment they spot water mentioned. That’s the shortcut to interrupt, more than the wrong verdict itself. You might ask them to check the other two criteria before they lock in an answer.
• One of the planets is built to catch that shortcut: right distance, stable tilt, but its ice sinks instead of floats. You could ask “If winter ice sinks to the bottom, can summer sun ever melt it?”
• It’s worth leaving a bit of extra time for whichever planet splits the room. That’s usually where the best discussion happens.

Plenary

• The reflective question asks learners to pick which loss would hurt life on Earth the most: water, the Moon or the Goldilocks Zone position. There’s no single right answer. What matters is whether the reasoning draws on evidence from the session rather than a guess.
• The lock-in is short this time, so it works to read it just as it is: “to attain any kind of life in this universe of ours appears to be quite an achievement.”