Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Module: Week 11 of 16 · Fall 2026 · in-person, two 75-minute lectures + one weekly lab
Objective covered: Objective 6 — Use Mendel's laws of segregation and independent assortment, with Punnett squares and the rules of probability, to predict the genotypes and phenotypes of offspring.

This file holds two pieces: (A) the Module 11 Overview page ("Start Here") and (B) the Welcome Announcement that drips out when the module opens. Dates below assume a Tuesday/Thursday lecture pattern with Week 11 meeting Tue Nov 10 and Thu Nov 12, a lab that same week, and end-of-week work due Sunday Nov 15, 11:59 p.m. Adjust the day-of-week and times to match your section.

(A) Module 11 Overview — Start Here

Welcome to Week 11: Mendelian Genetics

This is your home base for the week. Read it first, then work the checklist below from top to bottom. Everything you need is linked inside the module.

This is the week the course turns quantitative. For ten weeks we've defined life, built cells, run respiration and photosynthesis, and watched chromosomes divide. Now we answer the question every student secretly wants answered: why do offspring look the way they do — and can we predict it before they're even born? A monk named Gregor Mendel figured out the rules using pea plants in the 1860s, and those rules still let us calculate the odds of brown vs. blue eyes, of a recessive disease, of a tall pea or a short one. The tool is the Punnett square, and the math behind it is plain probability. Get careful with the arithmetic this week and the rest of genetics falls into place.

The week's big question

"Given the parents, what are the odds of each kind of offspring — and how do we calculate them instead of guessing?"

By Friday you'll be able to set up and fully work a Punnett square, read genotype and phenotype ratios off it, and use the product rule to find the probability of a specific cross — including the famous dihybrid 9:3:3:1.

By the end of this week, you can…

Use this as a checklist. If you can do all four out loud, you're ready for the quiz.

• [ ] Speak the vocabulary precisely — gene vs. allele, dominant vs. recessive, genotype vs. phenotype, homozygous vs. heterozygous — and explain why two organisms that look the same can cross differently.
• [ ] Fully work a monohybrid Punnett square (e.g., Tt × Tt) — fill all four boxes, then report the genotype ratio 1 TT : 2 Tt : 1 tt and the phenotype ratio 3 dominant : 1 recessive.
• [ ] Use probability — the product rule — to get P(recessive) = 1/4, P(dominant) = 3/4, and a test-cross Tt × tt → 1:1.
• [ ] Set up a dihybrid cross (TtYy × TtYy) and explain the law of independent assortment behind the 9:3:3:1 ratio, including P(ttyy) = 1/16 and P(both dominant) = 9/16.

What's due this week, and when

Work these in order — each one gets you ready for the next.

Heads-up on the AI tools: you'll use a chatbot to draft and explain, and then you judge its work against what we cover in class. Chatbots are notorious for garbling genetics ratios — they'll mislabel a 9:3:3:1, call a heterozygote "homozygous," or quietly drop a box from a Punnett square. Catching the model — and re-checking its arithmetic by hand — is the point this week, in the tutorial, the assignment, and the lab.

Late policy reminder: 10% off per day late. If life happens, reach out before the deadline — I'd much rather hear from you early.

How to succeed this week

• Nail the four vocabulary pairs first. Almost every mistake in genetics is a word mistake: confusing genotype (the alleles, e.g., Tt) with phenotype (the trait you see, e.g., "tall"), or homozygous (TT or tt) with heterozygous (Tt). Lock these before you touch a Punnett square.
• Memorize two tiny hooks. "Genotype is the recipe; phenotype is the cake." And "Each parent gives ONE allele — that's segregation."
• Always show every box. A Punnett square has four boxes for a monohybrid cross and sixteen for a dihybrid. Fill them all, then count. The ratio is just counting boxes. We will show every step in class, in the tutorial, and in the assignment — you should too.
• Treat ratios as probabilities. "3:1" means 3/4 dominant, 1/4 recessive. A Tt × Tt cross gives 3/4 chance of the dominant trait per child — but, like coin flips, a small family can land anywhere. The ratio is the long-run expectation, not a guarantee.
• Treat the chatbot as a smart intern, not an oracle. It drafts; you check its boxes and its fractions. That habit is the whole semester in miniature — and genetics is where AI slips the most.

You don't need anything but careful counting for this week. Bring a pen, two coins, and a willingness to double-check arithmetic. Come to class ready to predict the odds. See you Tuesday.

(B) Welcome Announcement — Module 11

Release setting: post on the module's start day (offset = 0 days), i.e., Tue Nov 10, 2026 — not before. If your platform won't preserve the scheduled date on import, post this as a draft labeled "Release: Tue Nov 10."

Subject: Welcome to Week 11 — can two brown-eyed parents have a blue-eyed child? 🧬

Hi everyone, and welcome to one of my favorite weeks of the whole course.

Quick warm-up before we start: two brown-eyed parents have a blue-eyed baby. Did the hospital mix up the babies? No — and by Thursday you'll be able to prove it with a four-box diagram and a little arithmetic. This week we meet Gregor Mendel, the monk who cracked the rules of inheritance with pea plants, and the tool that makes those rules predictive: the Punnett square. This is the week biology turns into a (very satisfying) probability puzzle.

This week — Mendelian Genetics — we tackle the big question: Given the parents, what are the odds of each kind of offspring, and how do we calculate them? By Friday you'll fully work a monohybrid Punnett square (and read the 3:1 ratio right off it), use probability to get P(recessive) = 1/4, and set up a dihybrid cross that lands on the legendary 9:3:3:1.

Three things not to miss:
1. Lecture Tutorial 11 — work through segregation, Punnett squares, probability, and the dihybrid cross with one approved chatbot (Gemini, Claude, or ChatGPT) and submit the share link. Genetics is where chatbots garble ratios most — catching that is the skill. Due Sun Nov 15.
2. Lab 11 ("Coin-Toss Genetics"), Quiz 11, Discussion 11, and Assignment 11 also close Sun Nov 15 — the lab has you flip two coins to model a real cross and compare your data to the predicted 3:1, so grab two coins and start early.
3. Open the Start Here page first — it lays out everything in order with due dates.

One promise: this is the week the vocabulary finally pays off. If you keep genotype and phenotype straight, and homozygous and heterozygous straight, the Punnett squares almost work themselves. We'll show every single box and every fraction in class — no hand-waving.

Bring a pen and two coins (a penny and a nickel are perfect) to class on Tuesday.

See you soon,
Prof. Castellano