Students explain that gametes have half the chromosome number and relate the features of sperm and egg cells to their jobs (AC9S9U02, node 1, a hinge node).
Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.
Engage and Explore 6 min · Explain 9 min · Plant gametes 3 min · Evaluate 3 min · Wider adds about 1 min
A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider.
The hinge misconception is that gametes have the full set of chromosomes. The Engage question asks it directly.
Board notes: diagrams are not to scale (a human egg is about 0.1 mm across, roughly 20 times the width of a sperm's head). The pollen grain carries the male nucleus; strictly, the male gametes form inside it.
Why a gamete needs half the chromosomes. When a student is stuck, ask how many chromosomes a fertilised egg would have if each gamete carried the full set.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says the baby gets half the genes. | How many chromosomes does the fertilised egg have? | 46: a full set, half from each parent. |
| A student thinks pollen is the plant's sperm and swims. | What carries pollen? | Wind or animals; then a pollen tube grows to the ovule. |
One possible solution for each task. Other correct programs are fine.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Stretch: Why do sperm need so many mitochondria, but egg cells don't need a tail?
Support: Give a labelled sperm and egg with the jobs listed in a box to match.
For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.
You are a patient science coach for a Year 9 student in Australia. Help me understand ONE idea only, from the lesson "What makes a sex cell special?". The idea: Reproductive cells — form matched to function: I can describe the structural features of male and female gametes and explain how each feature relates to the gamete's reproductive function. What understanding looks like: - Describes at least two structural features of sperm and two of egg cells - Explains how each feature relates to the gamete's function - Identifies plant equivalents (pollen, ovule) and describes one form-function relationship in each Mistakes students often make here: - A student says the baby gets half the genes. - A student thinks pollen is the plant's sperm and swims. How to coach me (rules from the Waypoints Kit coach): - Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question. - Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit). - If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go. - Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back. - After you help, ask me one reflective question, such as how I know my answer is right or what I would check. - Praise my effort and method, not my ability. - You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so. - Use simple words. - Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "What makes a sex cell special?".
Why do sperm and egg cells have 23 chromosomes, not 46?
So that when they fuse at fertilisation, the new cell has 46, the full number, again.
Next: sexual and asexual reproduction and variation (node 3). Year 10: meiosis, the cell division that halves the number.