5 mistakes learners make with reproduction, each one named and explained.
A new individual begins when a male sex cell and a female sex cell join, in animals and in plants alike.
You explain identical twins as two eggs fertilised at the same time.
Twins arrive together, so two of everything feels like the natural explanation.
Question. How do identical twins form?
A common answer. Two eggs are fertilised by two sperm at the same time
The answer. One fertilised egg splits into two, so both have the same genes
Why. Two eggs and two sperm gives non identical twins, who are no more alike than other siblings.
Count the eggs before you answer.
You say plants just grow from seeds, with nothing joining.
Nothing visible moves, there are no animals involved, and seeds look like a starting point rather than a result.
Question. Do plants have sex cells?
A common answer. No, seeds simply grow
The answer. Yes. The pollen nucleus is the male sex cell and the ovule holds the female one
Why. A seed is what is left after two sex cells have joined, exactly as in an animal.
Find the two cells that joined, in a plant as in an animal.
You say the flower is fertilised as soon as the bee leaves the pollen on the stigma.
They are taught together, one follows the other, and both are about pollen.
Question. What is the difference between pollination and fertilisation?
A common answer. They are the same thing
The answer. Pollination is pollen landing on the stigma. Fertilisation is the nuclei joining, after a pollen tube grows down
Why. Pollen arriving is delivery. Fertilisation is the two sex cells joining.
Name the two cells that join, and you have named fertilisation.
You put ovulation at day one of the cycle, alongside the bleeding.
Both are events of the same cycle, and only one of them is visible, so the timing of the other attaches itself to it.
Question. When in a 28 day cycle is the egg usually released?
A common answer. At the start, during the period
The answer. Around day 14, about halfway through
Why. The period is the lining breaking down after no fertilisation. Ovulation is roughly two weeks earlier.
Put both events on a timeline before answering.
You say the fetus breathes through the cord.
The fetus obviously needs oxygen and cannot breathe, so the cord gets described in the language of breathing.
Question. How does a fetus get oxygen?
A common answer. It breathes air through the umbilical cord
The answer. Dissolved oxygen passes from the mother's blood to the fetus's blood at the placenta, and travels in the cord
Why. The cord carries blood, not air. The lungs are not used until birth.
Say which substance is travelling, and in what.
WAJD spots these patterns in your child's answers and names the one behind their wrong answers, instead of just marking them wrong.