The shape of the lesson
By the end of the lesson, learners can
- Follow a star’s life: Watch a star form, live, and end in one of two ways depending on its mass.
- Two endings, set by mass: A Sun-like star fades to a white dwarf; a massive star explodes as a supernova.
- Shared start: nebula, protostar, main sequence.
- Low mass: red giant, planetary nebula, white dwarf.
- High mass: red supergiant, supernova, neutron star or black hole.
One picture every idea returns to
A star forms from a nebula collapsing under gravity into a protostar, then a stable star powered by fusion. A Sun-like star later swells into a red giant and ends as a white dwarf, while a much more massive star becomes a red supergiant, explodes as a supernova, and leaves a neutron star or a black hole.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Born, lived, gone.. Stars are born in clouds and die in two very different ways. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Follow a star’s life | Watch a star form, live, and end in one of two ways depending on its mass. Project tab 2 of the lab (Life cycle of a star) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Two endings, set by mass | A Sun-like star fades to a white dwarf; a massive star explodes as a supernova. | Corners |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 14 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Two endings, set by mass, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Corners
Put one answer or viewpoint in each corner of the room. Students move to the corner they agree with, justify the choice to a partner there, then hear one voice from each corner before the reveal.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| How a star ends depends on its mass. | A star like the Sun becomes a red giant then a white dwarf, but a much more massive star explodes as a supernova and leaves behind a neutron star or a black hole. |
The life cycle of a star: worksheet
6 questions, 14 marks. Written in the style of the papers; no past paper question is reproduced.
Name, in order, the first three stages in the life of any star.
Describe the final stages of a low-mass star like the Sun, after the main sequence.
Describe the final stages of a high-mass star after the main sequence.
Explain why a main sequence star stays the same size for a long time.
State the single property of a star that decides whether it ends as a white dwarf or as a neutron star or black hole.
A student says the Sun will one day explode as a supernova. Explain why this is wrong and state what will actually happen to it.
Answer key and marking notes
- Nebula. ✓
- Protostar. ✓
- Main sequence star. ✓
- It becomes a red giant. ✓
- It throws off its outer layers as a planetary nebula. ✓
- It ends as a white dwarf. ✓
- It becomes a red supergiant. ✓
- It explodes as a supernova. ✓
- It leaves a neutron star, or a black hole if massive enough. ✓
- Gravity pulls the star inwards. ✓
- The outward push from fusion balances gravity, so the star is stable. ✓
Its mass. ✓
- The Sun is a low-mass star, and only high-mass stars end in a supernova. ✓
- It will become a red giant, then a planetary nebula, and end as a white dwarf. ✓
3 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
A star begins to form from a cloud of gas and dust. What is the correct early sequence?
- Anebula, then protostar, then main-sequence star
- Bmain-sequence star, then protostar, then nebula
- Cnebula, then white dwarf, then protostar
- Dprotostar, then nebula, then supernova
A star about the size of our Sun runs low on hydrogen near the end of its life. What is its likely sequence?
- Ait swells into a red giant, then becomes a white dwarf
- Bit explodes as a supernova, then becomes a black hole
- Cit stays a main-sequence star forever
- Dit collapses straight into a neutron star
A star much more massive than the Sun reaches the end of its life. What can happen?
- Ait becomes a red supergiant, explodes as a supernova, and leaves a neutron star or black hole
- Bit quietly becomes a white dwarf like the Sun
- Cit turns back into a nebula and does nothing else
- Dit becomes a planet
Quiz key
A star forms when gravity pulls a nebula together into a protostar; once it is hot and dense enough for steady fusion, it becomes a main-sequence star. The other sequences are out of order.
A Sun-sized star expands into a red giant, then sheds its outer layers and leaves a hot, dense white dwarf. Supernovae, neutron stars, and black holes are the fate of much more massive stars.
A very massive star swells into a red supergiant and then explodes as a supernova, leaving behind a neutron star or, if massive enough, a black hole. Only lower-mass stars end as white dwarfs.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.