Teacher sheet · Ages 15–16 · about 45–50 minutes
Growth, puberty and the human lifespan
Lesson page: echoesof.science/school/growing-up/ages-15-16/ · Pupil worksheet: echoesof.science/school/growing-up/ages-15-16/print/
Learning aims
- Describe prenatal stages and infant growth with numbers and units.
- Calculate and interpret growth velocity, including rounding uncertainty.
- Explain the hormonal control of puberty (GnRH, FSH, LH, testosterone, estrogens) and negative feedback.
- Interpret life expectancy and healthy life expectancy statistics critically.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: why do growth charts use velocity as well as height? |
| 10 min | Read the text; draw the hormone cascade together. |
| 20 min | Growth-velocity data analysis in pairs. |
| 5 min | Uncertainty and the shape of the full growth curve. |
| 5 min | Quiz, or the Where is it made? game as homework. |
Materials for the experiment
- Graph paper or a spreadsheet
- Calculator
- The data table on the worksheet
- Optional: anonymised, published growth-chart data provided by the teacher
Safety: This is a data analysis: no measurements of pupils are needed. If you use class data, collect it anonymously and voluntarily; never display individual pupils' heights or weights. Growth questions about a particular person belong with a doctor or the school nurse.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Growth is fastest in puberty. | Growth velocity is highest just after birth; it falls rapidly, then rises again in the adolescent spurt. |
| Testosterone is made in the brain. | The brain (hypothalamus and pituitary) controls it; testosterone is made by the Leydig cells in the testes. |
| Life expectancy is the age everyone will reach. | It is an average for a whole population; individuals vary widely, and figures differ between countries. |
Worksheet answers
- 0–12 months: 74.9 − 49.5 = 25.4 cm/year; 12–24 months: 87.4 − 74.9 = 12.5 cm/year; decrease = (25.4 − 12.5) ÷ 25.4 × 100 ≈ 51%.
- Hypothalamus → GnRH → anterior pituitary → FSH and LH → testes (testosterone) or ovaries (estrogens, progesterone); negative-feedback arrow from testosterone back to the hypothalamus and pituitary.
- Life expectancy (71.4 years) is the average number of years a newborn could expect to live; healthy life expectancy (61.9 years) is the average number of those years lived in good health; the difference is about 9.5 years.
- Each length can be out by 0.05 inch ≈ 0.13 cm, so the difference can be out by about ±0.25 cm/year.
Quiz answers
- Which hormone does the hypothalamus release to start the puberty cascade? GnRH. GnRH from the hypothalamus makes the anterior pituitary release FSH and LH.[5]
- In males, LH stimulates which cells to make testosterone? Leydig cells in the testes. LH acts on the Leydig cells.[5]
- Rising testosterone reduces GnRH release. This is an example of… negative feedback. The product of the pathway inhibits an earlier step.[5]
- Length rises from 49.5 cm to 74.9 cm in 12 months. What is the growth velocity? About 25 cm/year. 74.9 − 49.5 = 25.4 cm in one year.[1]
- Global life expectancy was 71.4 years and healthy life expectancy 61.9 years (2021). On average, how many years were lived in less than full health? About 9.5 years. 71.4 − 61.9 = 9.5 years.[6]
- A newborn's head is about a quarter of its length; an adult's about a seventh. This shows that… the body and legs grow proportionally more than the head. Different parts grow at different rates.[4]
Going further
Compare published growth charts from two countries and discuss why reference curves differ. Handle the topic sensitively: never use individual pupils' data, and remind pupils that a wide range of growth patterns is normal.
Sources used in this lesson
- [1] Psychology 2e, 9.3 Stages of Development (OpenStax, Rice University): reliability High
- [2] Early or delayed puberty (NHS (UK National Health Service)): reliability High
- [4] Human development (Encyclopaedia Britannica): reliability High
- [5] Biology 2e, 43.4 Hormonal Control of Human Reproduction (OpenStax, Rice University): reliability High
- [6] COVID-19 eliminated a decade of progress in global level of life expectancy (news release, 24 May 2024) (World Health Organization (WHO)): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/growing-up/sources/
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