Lesson 1 of 6 · Genetics
Meiosis Halves the Number and Shuffles the Deck
🧬
🎯 Your mission
Set it up. Test it. Be amazed.
⚡ The twist
Nature loves to surprise the careful watcher.
What you'll learn
Meiosis makes gametes carrying 23 chromosomes from cells carrying 46, but halving is only half of what it does. Homologous pairs line up and exchange segments in crossing over, and each pair orients independently at the metaphase plate, so a single person can produce more than eight million chromosomally distinct gametes before crossing over is even counted. Fertilisation then combines two of those at random, which is why siblings from the same parents differ.
Key words
meiosis
The cell division producing gametes with half the chromosome number, and shuffling the alleles as it does so.
crossing over
The exchange of segments between homologous chromosomes during meiosis, creating new allele combinations.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
Say your guess out loud — then find out if you were right.
Get ready
🧰 What you need
- pipe cleaners in two colours
- scissors
- sticky labels
- notebook
⚠️ Safety first
- Use scissors carefully and cut away from your fingers.
Step 1 of 4 · Read
Think about what you just learned: say what "meiosis" and "crossing over" mean in your own words before you start.
Step 2 of 4 · Do
Model meiosis with two colours of pipe cleaner as homologous chromosomes. Run independent orientation for three pairs, listing every combination you can produce, then twist and swap segments to add crossing over and count how many more combinations appear.
Step 3 of 4 · Observe
Record what actually happened, including anything that did not match what you expected.
Step 4 of 4 · Record
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Question 1 of 3
Question 2 of 3
Question 3 of 3
Mind = blown
🔬 The more you look, the more nature shows you.
Nice work!
You got 0 of 3 right.
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✨ More to explore
🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.
🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.
👨👩👧 For the dinner table: “What's the most surprising thing you learned today?”
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Ready?
Meiosis Halves the Number and Shuffles the Deck
Set it up. Test it. Be amazed.
Full screen — no distractions
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Print the whole Genetics track
All 8th Grade Genetics lessons as a printable PDF, with worksheets and answer keys.