DSE Biology | Human Reproduction and the Menstrual Cycle: Tutor Lesson Plan (28-day timeline, four hormones, fertilisation to implantation)

2026-11-02

Tutor lesson-prep guides · Secondary Biology

Students can recite that ovulation happens on day 14, yet go blank when asked when progesterone rises and why. This lesson ties the four hormone curves to the two possible outcomes on one 28-day axis.

Objectives — By the end students can: (1) state the function of each part of the male and female reproductive systems and say where gametes are made and where fertilisation occurs; (2) draw the FSH, LH, oestrogen and progesterone curves over a 28-day cycle and explain why ovulation falls near day 14; (3) trace fertilisation through to implantation and explain why the corpus luteum does not degenerate in pregnancy.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Cell division	What does meiosis do to the chromosome number?	46 (2n) becomes 23 (n)
Hormones	How do hormones travel and where do they act?	In the blood, on specific target cells
Reproductive organs	Where are sperm and eggs produced?	Testes and ovaries

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-5 min	Opening question	Write “28” on the board and ask what this number stands for in this unit	Hands up; say what they remember
5-15 min	Prerequisite check	Hand out three quick items (meiosis, hormone transport, gamete organs)	Written answers, marked aloud
15-37 min	Three-act teaching	Deliver the scripts on organs and gametes, the four cycle hormones, fertilisation to implantation	After each act, one sentence: hormone rises, then what happens
37-49 min	Worked question types	Model four questions, each as hormone, tissue response, outcome	Copy, then rewrite unaided
49-55 min	Independent practice	Circulate; ask only “which day does this curve peak?”	Do three items and self-mark
55-60 min	Exit check	Collect answers and count errors on the spot	Written, no talking

03 Teaching script (read it out)

Scene 1: Act 1: Reproductive organs and gametes

Start with production versus transport. Male: sperm are made in the seminiferous tubules of the testes, stored and matured in the epididymis, carried by the vas deferens, and mixed with fluids from the prostate and seminal vesicles; the urethra carries both urine and semen. Female: the ovaries make eggs and secrete oestrogen and progesterone, the oviduct (Fallopian tube) is where fertilisation happens, the uterus lining is where implantation happens, and cervical mucus changes through the cycle. Both gametes are haploid with 23 chromosomes, so the zygote is back to 46 – this answers the common question of why chromosome number does not double each generation. All eggs are formed before birth and normally only one matures per cycle; sperm are produced continuously. That asymmetry underpins every later question.

Why must fertilisation happen in the oviduct rather than the uterus?

Scene 2: Act 2: Four hormones across 28 days

Walk one 28-day timeline in order. Days 1-5: oestrogen and progesterone are low, the lining breaks down, menstruation. FSH from the pituitary then matures a follicle, which secretes oestrogen; oestrogen thickens the lining and at high levels exerts negative feedback on FSH while priming the LH surge. Near day 14 oestrogen peaks and triggers a sharp LH surge; ovulation follows about 36 hours later. The follicle becomes the corpus luteum and secretes progesterone, which maintains and vascularises the lining and suppresses FSH and LH. Without pregnancy the corpus luteum degenerates after about 14 days, hormones fall, the lining loses support and sheds, and a new cycle begins. One sentence to keep: progesterone holds the lining, so when it falls, menstruation follows.

If the LH surge never happened, what would happen to this cycle?

Scene 3: Act 3: Fertilisation, implantation and pregnancy

Sperm survive about 72 hours in the female tract; an egg can be fertilised for about 24 hours after release. Together that is 96 hours, roughly four days – the fertile window, not “day 14 only”. Fertilisation occurs in the ampulla of the oviduct: the acrosome releases enzymes through the egg coverings and one sperm nucleus fuses with the egg nucleus, forming a diploid zygote and immediately blocking other sperm. The zygote divides by mitosis while travelling down the oviduct, reaching the uterus in about five to seven days and implanting. The embryo then secretes hCG, which maintains the corpus luteum, so progesterone stays high, the lining is not shed and menstruation stops – the basis of a pregnancy test. From the first day of the last menstrual period pregnancy is about 280 days (40 weeks); from fertilisation it is about 266 days. Keep the two starting points apart.

Why does menstruation stop in pregnancy? Answer with the corpus luteum and progesterone.

04 Question types and worked steps

Type	Example	Steps	Answer
Structure and function	State two functions of the oviduct in reproduction.	1) Transport the egg by cilia and peristalsis; 2) site of fertilisation; 3) carry the embryo toward the uterus; 4) one explanation per point.	Example: fertilisation occurs in the ampulla.
Hormone curve description	Describe the change in progesterone during the menstrual cycle.	1) Three phases: low during menstruation, low before ovulation, rises after; 2) peak around day 21; 3) falls if no pregnancy; 4) explain via corpus luteum formation and degeneration.	Example: after ovulation the corpus luteum raises progesterone for about 14 days.
Cause and effect (feedback)	Explain how progesterone affects FSH and LH secretion.	1) State the pituitary and hypothalamus as targets; 2) inhibits FSH and LH; 3) so ovulation is not repeated in the same cycle; 4) close with the term negative feedback.	Example: high progesterone suppresses FSH and LH.
Application (contraception, testing)	Combined oral contraceptives contain oestrogen and progesterone. Explain how they prevent pregnancy.	1) Hormone levels stay high; 2) negative feedback suppresses FSH and LH; 3) follicles do not mature and ovulation does not occur; 4) cervical mucus and lining also change.	Example: the core mechanism is anovulation, not sperm killing.

Sanity check (teach this): Sanity checks: 28 minus 14 leaves a fixed 14-day luteal phase, so menstruation starts around day 29; a student who says the luteal phase lengthens has mixed up hormones with time. 40 weeks is 280 days and subtracting the 14 days before ovulation gives 266 days from fertilisation. Sperm at 72 hours plus egg at 24 hours gives 96 hours; answering “24 hours” omits sperm survival. Keep 23 chromosomes distinct from 23 pairs – “an egg has 23 pairs” is out by a factor of two.

05 Independent practice (3 questions)

Question	Answer	What to watch
State where fertilisation occurs and why not in the uterus.	Oviduct (ampulla); the egg enters the tube, sperm swim up to meet it, and only the zygote is moved to the uterus for implantation.	Watch for implantation site given as fertilisation site.
If no fertilisation occurs, how does progesterone change near day 28 and why?	The corpus luteum degenerates, progesterone falls, and the lining is shed.	Watch for the reversed claim that rising progesterone causes menstruation.
Explain why menstruation stops in pregnancy using hormones.	The embryo secretes hCG, maintaining the corpus luteum, which keeps secreting progesterone so the lining is retained.	Watch for “because she is pregnant” with no hormonal mechanism.

06 Common mistakes and what to say

Mistake	Student writes	Say this
Confusing fertilisation with implantation	Writing that fertilisation happens in the uterus and implantation follows.	“Fertilisation is in the oviduct. The embryo takes days to reach the uterus. Two separate locations, two separate lines.”
Reversing hormone roles	Writing that a rise in progesterone triggers ovulation.	“Ovulation follows the LH surge. Progesterone comes after ovulation, from the corpus luteum. Reverse the order and the whole answer fails.”
Fertile window given as one day	Writing that conception is only possible on day 14.	“Sperm live about 72 hours and the egg about 24, so roughly four days. The days before ovulation count too.”
Mixing the two pregnancy counts	Writing that 40 weeks means 280 days after fertilisation.	“40 weeks is counted from the last menstrual period; from fertilisation it is about 266 days. Always state the starting point.”

07 Homework (paper, section and question numbers)

Secondary Biology chapter index: finish the three items on this page, then compare with the cell division chapter for chromosome numbers — Practice 1-3 on this page

08 Exit check (last 5 minutes)

Question	Answer	Decision
Where does fertilisation occur?	Oviduct (ampulla)	Cannot answer: reteach Act 3
Which hormone surge triggers ovulation?	LH	Cannot answer: reteach Act 2
How long does the corpus luteum last without pregnancy?	About 14 days	Cannot answer: reteach Act 2

09 Tutor FAQ

Which year is this for?

Mainly S5 Biology in the reproduction and genetics unit; S4 classes that have covered cell division can start here, since the 2n and n comparison carries over.

Must students memorise four curves?

They need the shape and the causation, not absolute concentrations. Four turning points are enough: FSH rise, oestrogen peak, LH surge, progesterone peak.

Is there paired practice?

The homework link goes to the biology chapter index; teaching it beside the cell division chapter links the 2n and n arithmetic directly.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.