Teaching genetics and heredity might just be my favorite unit in my biology class. I find the content fascinating and with so many real life examples students have a much easier time making connections compared to teaching DNA, cell division, or photosynthesis. My students already have a good grasp on understanding probability when they get to my class so teaching the likelihood of a genetic cross occurring isn’t a stretch. They can also think of traits that run through their family (such as height or eye color) and make connections with other traits being taught. Here are 5 tips for teaching genetics and heredity to help your students learn this important content.
Use the story of Gregor Mendel In Your Lectures
As often as possible, I try to teach biology as a series of events that are linked together. From there it’s easy for kids to remember key events and interweave the content being taught versus learning a bunch of vocabulary terms in isolation and then trying to explain what they mean. My lectures on Gregor Mendel and the discovery of modern genetics definitely follow this pattern. We discuss the life of a monk in the mid 1800’s and Mendel’s methodical process for collecting and documenting his results from crossing different parental varieties of pea plants. In my lectures we take a deep dive into mendelian genetics and why we see the receive phenotype disappear in the F1 generation only to reappear in the F2 generation in a 3:1 ratio.
Don’t Forget About Non Mendelian Genetics
After lecturing on the discoveries of Gregor Mendel and the mathematical probability that we see with his genetic crosses, I take it further by explaining that not all traits follow the same rules. In my biology classes we focus deeply on both incomplete dominance and codominance as examples of non mendelian genetics. Using pictures to help reinforce these topics can go a long way with student comprehension. For incomplete dominance, I like to use flowers as my example. My students already have a good understanding of how paint colors blend together so this just takes it one step further when we link the phenotypes seen with the genotypes for a specific trait.
Codominance is generally the first time I go into details with human traits. Many kids know their blood type so we get to have discussions about what it means to be Type O, Type A, Type B, and Type AB. Like with incomplete dominance, the use of pictures can make a big difference in if my students understand a topic or not. Again, this is a great chance to build a deeper understanding of the connection between genotypes and phenotypes.
Build Mastery With Punnett Squares Practice Worksheets
Throughout my genetics and heredity unit punnett squares help my students put the concepts we are discussing into practice. We get to talk about predicting the outcomes of genetic crosses and students get to reinforce key vocabulary terms. Throughout my genetics unit I use four different punnett square worksheets for guided practice. We start with our monohybrid cross worksheet and dihybrid cross worksheet to build understanding of mendelian genetics. And then as lectures discuss non mendelian genetics, students work on incomplete dominance and codominance punnett squares. Finally, students complete the sex-linked trait worksheet with the final lectures in our unit.
Teach Meiosis With Genetics (Not Mitosis)
When I first began teaching biology 20+ years ago I would teach mitosis and meiosis together. I think I did so because that’s what the veteran teachers in my department had always done. Unfortunately, many students got confused with teaching meiosis without having any context of genetics and heredity. I found that when I teach mitosis and the cell cycle early in the year with the other chapters about cells my students aren’t as overwhelmed. And then when we cover meiosis later in the school year, kids can make connections and seem to get a better grasp of the content.
Include A Pedigree Lab Activity In Your Unit
One of the last activities I teach in my genetics and heredity unit is how to read pedigrees to make genotype and phenotype predictions. I group pedigrees with sex-linked traits in lecture and then we go through a few examples in class of how to use them to work backwards to determine parental genotype based on the results of the offspring. This building into my pedigree lab activity. Since it’s a no-prep lab, this can also be done at home (I also have a digital version) if we are running short on time. My students really seem to like pedigrees and we can make connections to family lineages and the passing on of traits through generations.
Final Thoughts…
Genetics can be a make or break unit in your class. Hopefully these 5 tips help your students improve their understanding of this key topic. It’s definitely one of my favorites and I look forward to teaching genetics and heredity every year.
