Teacher sheet · Ages 10–11 · about 45–50 minutes
Life cycles and metamorphosis
Lesson page: echoesof.science/school/animal-life-cycles/ages-10-11/ · Pupil worksheet: echoesof.science/school/animal-life-cycles/ages-10-11/print/
Learning aims
- Define metamorphosis and compare complete and incomplete metamorphosis.
- Describe the life cycles of a butterfly, a frog, a bird and mammals.
- Use a scale to represent time.
- Plan a fair test, identifying independent and control variables.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: is a tadpole a fish? Is a caterpillar a worm? |
| 10 min | Read the text; compare the life cycles in a table. |
| 20 min | A frog's life to scale. |
| 5 min | Plan the temperature fair test (no live animals). |
| 5 min | Quiz or the Complete or incomplete? game. |
Materials for the experiment
- A long strip of paper (at least 2 m, or tape several sheets together)
- Metre stick or tape measure
- Coloured pens
- Calculator
Safety: Use a clear floor or corridor and keep the strip flat so nobody trips. This is a modelling and planning activity: do not take frogspawn or tadpoles from the wild.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| All insects have a pupa stage. | Grasshoppers, cockroaches and dragonflies have nymphs and no pupa. |
| The caterpillar just grows wings inside the chrysalis. | Its body breaks down and reorganises into the adult. |
| All mammals give birth to live young. | Monotremes (platypus, echidnas) lay eggs. |
Worksheet answers
- Complete: egg, larva, inactive pupa, adult (e.g. butterfly, beetle). Incomplete: egg, nymphs that look like small adults and moult, adult (e.g. grasshopper, dragonfly).
- Hatching at 3 weeks, legs from 19 weeks, so the tadpole stage is roughly 16 to 20 of the 104 weeks: about a sixth or a fifth.
- Change: water temperature. Keep the same: food, amount of water, light, number of tadpoles, size of container, and measure the same thing (e.g. days until legs appear).
- 19 days.
Quiz answers
- What are the stages of complete metamorphosis? Egg, larva, pupa, adult. Complete metamorphosis has a pupa stage.[3]
- Which insect goes through incomplete metamorphosis? A grasshopper. Grasshoppers have nymphs, not a pupa.[3][4]
- How does a nymph grow? By moulting, shedding its skin. Insects shed their skin to grow.[3]
- About how many times its birth weight can a caterpillar grow? About 1,000 times. Caterpillars eat a lot and grow enormously.[1]
- How do young tadpoles breathe? With gills. Lungs form later, during metamorphosis.[2]
- Which mammals lay eggs? The platypus and echidnas. Monotremes lay soft-shelled eggs; kangaroos are marsupials.[7]
Going further
Compare with a human life cycle: which animal spends the largest fraction of its life as a juvenile? Use pictures and videos; if the school uses a classroom butterfly kit, follow the supplier's care and release guidance.
Sources used in this lesson
- [1] The Butterfly Life Cycle Explained (American Museum of Natural History): reliability High
- [2] Frogspawn, tadpoles and froglets (Natural History Museum, London): reliability High
- [3] What is Metamorphosis? (Australian Museum): reliability High
- [4] Insect Metamorphosis: The Key to a Fresh New Start (Carnegie Museum of Natural History): reliability High
- [5] Animal development: Metamorphosis (Encyclopaedia Britannica): reliability High
- [6] Stages of Chick Embryo Development (Mississippi State University Extension): reliability High
- [7] Mammals (Australian Museum): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/animal-life-cycles/sources/
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