Chromosomes in a Bag Activity

If you teach health or life science to middle schoolers, then this is a lesson you may want to do with your students when you are in your teaching the genetics behind how one is born a male or a female. This activity is great for your visual learning kiddos. It uses repetition and pictures to help students see just how it is that the father’s chromosomes determine a child is born a girl or a boy. Everything you need for this lesson can be found here:

If you talk to middle schoolers, you will see that most do not know what chromosomes even are, let alone how chromosomes, sex chromosomes in particular, determine whether one is born a girl or a boy. Most students at age 12 do not know the difference between the male and female reproductive cells and how the come together to form a single cell called a zygote, that will divide to become an embryo, then a fetus, and then a baby. Well, the point of this lesson is for students to learn whose sex chromosome determines whether the baby is a girl or a boy.

How they themselves were born a baby girl or boy, they are not sure. Most just know it has something to do with genes, and that we get our genes from our mom and dad. Most don’t even know what a gene or chromosome even is-it's just a word they have heard before. This a wonderful introductory lesson for knowing just how it is they we were either dressed in pink or blue as a newborn baby.

It is in seventh grade when students are usually introduced to this topic. This particular chromosomes-in-a-bag activity is a favorite teaching tool of mine for learning about the male and female gametes and their chromosomes. This lesson helps students see how the sex of a child is inherited using labeled X and Y cards.

To begin, have students partner up with another student. Each pair of students will receive two brown sac bags each (do not use see through bags). One bag will be labeled Dad’s Chromosome and the other bag will be labeled Mom's Chromosome. The bag labeled Dad's Chromosomes will contain one X and one Y card, and the bag labeled Mom's Chromosomes will contain two X cards, like shown in the picture below.

Students will take turns drawing one card from their bag. One student will be the dad in this activity and ONLY draw a card from the dad bag without looking to see what they get (no peeking!). The other student will be the mom in this activity and ONLY draw a card from the mom bag. Mom bags will only have only X chromosome cards and the dad bag will have an equal number of X and Y cards. As they take turns drawing they will record their data. At the end, they will count how many were girls and how many were boys and calculate the percentages.

Mom's Sex Chromosomes

Dad's Sex Chromosomes

My Is it a Girl or Boy Activity download contains a worksheet for students to write down their results and an instructions page on how to do this with your class. Go ahead and try this the next time you are teaching the unit covering this topic. I think you will find it a successful learning tool to use again and again in your classes. Just laminate the chromosome cards and save them in plastic bags to use for years to come! Teach with a Buzz!

*Before starting this activity, you will want to teach students that the reproductive cell in females is the egg, while the reproductive cell in males is the sperm. Egg cells can only have an X chromosome, while sperm cells can have either an X or Y chromosome, this is why the male's chromosome determines whether a baby will be a girl (XX) or a boy (XY).

Extension

Get your students curious! Tell them about some exceptions to this rule that all females are XX and all males are XY. Teach them about some rare genetic disorders like Supermale Syndrome where a man can have an extra Y chromosome (XYY) or Klinefelter's, where a male can have an extra X chromosome (XXY), and Turner's Syndrome, where a female can be missing an X chromosome (X), and Trisomy X, where a female can have an extra X chromosome (XXX). That will get them thinking!