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Mistakes teachers make when teaching biology

teaching biology

Let’s be honest – there is only so much we can learn in our undergraduate courses, student teaching experiences, and alternative certification programs. At the end of the day, so much that I’ve learned about being a teacher, and teaching biology specifically, has been through trial and error. If we want to get fancy, we can call it “action research” in my own classroom, as my graduate professors referred to it.

Bless my poor student guinea pigs – amiright?!

I made a ton of mistakes in my first few years teaching, in particular, and I know I still have so much I can learn (which is one of the main reasons why I make it a priority to bring in guests to the Secondary Science Simplified™️ podcast!!)

But even though I am still in the learning process, I wanted to share with you the 4 BIGGEST mistakes I made when teaching biology that I’ve learned from, in the hopes of preventing other biology teachers from making the same mistakes and having to learn (at the expense of your students) the hard way!

Mistake #1 when teaching biology: Teaching macromolecules in an isolated biochemistry unit.

teaching biology

When you look at the ENTIRE scope of topics covered in a traditional biology 1 course, macromolecules are truly foundational to EVERY SINGLE topic. So why is it that it has become standard practice to teach the biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids) in an isolated biochemistry unit?

If you are teaching biology this year, I urge you to consider teaching macromolecules:

  1. EARLY in your unit sequence, and
  2. Integrating them into every subsequent unit thereafter.

I like to kick off the year teaching them in my Biology Basics unit, and I make a point in EVERY SINGLE UNIT the rest of the year to incorporate macromolecules. There is not a single unit test of mine that doesn’t have at least one question related to carbs, lipids, proteins, or nucleic acids.

I also like that it sets the precedent from our very first unit that all of biology builds on itself and is integrated. You can’t just cram the night before the test to make it through the unit – I want my students to know that true understanding is required for them to have success the ENTIRE year because none of the topics are really “one and done” when teaching biology.

An additional suggestion – make the focus on their functional uses for maintaining life, not their structural components. While YES structure is important (form dictates function, after all) and will absolutely be essential understanding if they go on to later take AP biology, at this foundational Biology 1 level, the most important thing is that our students REALLY see how essential these molecules are to the functioning of life.

Mistake #2 when teaching biology: Teaching biochemical reactions on only a micro level.

teaching biology

At my first teaching job, I taught on a team of four biology teachers. We were required to collect and analyze LOTS of data, which was a tedious and cumbersome task. But we did learn a lot from doing this, and one of the things we saw was that our students were consistently – every semester, in each of our classrooms – bombing our biochemistry unit.

This unit included: macromolecules, enzymes, ATP, photosynthesis, and cellular respiration. So yea, it was a doozy. SHOCKER that we had test averages in the low 60s, right??

We initially tried to solve the problem by dividing the unit in half. But even chunking it up was still too much.

One teacher brought up the idea of pulling food webs and trophic pyramids out of our Ecology unit and teaching it alongside photosynthesis and cellular respiration. Ecology was traditionally our easiest unit with the highest scores from students, so it made sense to pull a topic from it and bring it into our hardest unit to try to boost the test scores a bit with some easier questions.

But what we found was SO much richer than simply a higher end-of-unit test average. Students were actually understanding photosynthesis and cellular respiration as biochemical reactions WAY better on a micro level when they were seeing the impact that these processes had on a macro level when it came to the transfer of energy from producers to consumers in food webs and trophic pyramids.

This led to the reframing of the entire biochemistry unit as the “Energy Flow Unit” with the focus being on how energy flows on every biologically level – micro in our cells, and macro in our ecosystems.

Side Note: After revamping our biochemistry unit as a team in this way, I went on the next school year to teach at a different school where I had five preps, all to myself, and total autonomy. At this time I decided to pull macromolecules out of the Energy Flow unit and teach them at the very beginning of the year, in a unit I call Biology Basics. This was an absolute game-changer, and the start of me correcting mistake #1 of teaching macromolecules in isolation.

You can read more about my biology scope and sequence, if interested, here.

Mistake #3 when teaching biology: Teaching mitosis and meiosis together.

teaching biology


Okay, forgive me for shouting at you, but I need you to hear through this screen how important this is!!

Let me back up by starting with a confession – I distinctly remember teaching these in sequence during my student teaching experience, as most teachers do during a cells unit, and being just about as confused as my students were. It was hard for ME as the teacher (albeit, a rookie one) to keep prophase, prophase I, and prophase II straight, so of COURSE it was nearly impossible for my students.

Not only do they have a LOT of variations of the same term to keep squared away, but they are also trying to understand the distinctions between DNA, chromosomes, genes, sister chromatids, and homologous chromosomes. Throw in diploid and haploid and their brains are just about completely fried.

When I got my first teaching job, I KNEW I had to do something different with these two processes, and a teacher on my team recommend teaching them completely separately.

**Mitosis during my Cells unit**

**Meiosis later on during my Genetics unit**

This was revolutionary in understanding for me AND my students!! Why??

  • The processes do not HAPPEN in sequence – so why do we teach them in sequence??
  • The processes have ENTIRELY different purposes – thus teaching them alongside content that more closely relates to the purpose of the process is incredibly helpful for context.
  • Distancing them makes it MUCH easier to see the processes individually, and to keep them filed in the brain separately, rather than in conjunction with each other.
  • If you teach them separately in this way, you can get students squared away with DNA, chromosomes, and sister chromatids terminology first when you teach mitosis.
    • Then a few months later, you can add the additional layer of vocabulary that homologous chromosomes, diploid, and haploid brings to the table. It chunks it up for students and makes it WAY less overwhelming.

If you are reading this mid-school year while teaching biology, I know it can be a LOT to change up your unit sequence and lesson plan organization once you’ve gotten started, but I urge you to consider making this change RIGHT AWAY if you have yet to teach cell division this year!!

(Note: I felt so passionately about this I ended up writing an entire additional blog post about it so if you want even more reasons why you should teach mitosis and meiosis separately, check out this post here).

Mistake #4 when teaching biology: Allowing misconceptions to fester when teaching evolution.

teaching biology

I was so nervous to teach evolution for the first time that I was extremely avoidant in a LOT of the areas where I didn’t personally feel confident in my knowledge and ability to provide answers to their questions.

As I grew in my own knowledge, understanding, and confidence, I was able to actively expose, address, and correct misconceptions in regards to evolution, and it helped SO MUCH with students’ understanding.

In fact, I actually like to expose my students’ misconceptions RIGHT AWAY by starting the unit with a survey to bring to light any misunderstandings before we can even dive into the content. You can get this survey for free, and read more suggestions specifically for teaching evolution at this post here.

A few additional tips when teaching biology for your consideration:

  • If traditional biology labs aren’t working for you and your students, CHANGE THEM! I was forced to get extremely creative at my most recent teaching gig because I had no lab space or science budget. This resourcefulness forced me to come up with new ways to teach a lot of old topics, and I feel like students learned a lot of things even better than before!
  • Create space in your unit plans for incorporating phenomena and real-world connections with your students. There are so many amazing ones relevant to teaching biology!!
  • Get students outside as much as you can! Biology is the study of LIFE and our students spend a LOT of time disconnected from real life because they are so OVER connected to their screens.
    • I highly recommend investing in a class set of clipboards so you have the flexibility to go outside any time your students are working independently or in groups and the weather is cooperative!

What additional mistakes have YOU learned from your time teaching biology? I would LOVE to hear! You can reach out to me via DMs on Instagram here, or by contacting me via email here.

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