A Unit Study on DNA for Middle Schoolers
Winter is often a time to mix things up for homeschoolers. It is also a time where I find myself letting go of the rigidity of the curriculum I’ve purchased and start to play a little more with ideas. I have a sense of how it fits us and what we find interesting, and I feel more free to mix-and-match.
We just finished a unit study on DNA and inheritance that I thought I’d share in case you wanted some ideas for Science this winter.
My Intention:
My intention with this unit was to expose my kids to heredity in the context of evolution and the development of life on earth. I wanted to pair biology lessons with history and explore how ideas evolve over time. I always try to approach these topics in a spirit of curiosity and openness to go as deep (or shallow) as we want to, following our inspiration until it is no longer fun.
This unit fits into a bigger year-long exploration on Becoming a World Citizen that we are doing, as outlined in my curriculum plan for this year.
The Resources:
I mainly used The Big History Project (BHP) as a jumping off point (a fantastic free curriculum and resource), and supplemented with Building Foundations of Scientific Understanding (vol 3) (BFSU) and Real Science Odyssey’s Biology 2 lessons. This chart shows how I organized and sequenced the lessons. We did supplement with many of the additional resources below.
The Plan:
You can see that the lessons are organized around themes:
Scientific Thinking
I started with a background of scientific thought, where we looked at how our understanding of heredity has changed over time. Using Mendel’s curiosity as a jumping off point for how scientists approach topics and the process they use to dig deeper, we discussed what it means to maintain scientific integrity. We used Part 1-4 of the BFSU B-27 lesson (Heredity, Genetics, and DNA) to bring ourselves up to speed on the theories and major players.
Goldilocks Conditions For Life
Then we explored the goldilocks conditions for life on earth using the Big History Project Unit 5. This unit examines what makes life special and how life emerged and diversified. It uses mysteries in science to draw students in, allowing them to participate in the inquiry process. In Lesson 5.0 (What is Life?), we explored the definition of life, realizing that it isn’t as straight-forward as we thought. In Lesson 5.1 (How Did Life Begin and Change?), we looked at how scientists have tried to understand how life happened and what conditions made it possible for life to emerge on Earth. In Lesson 5.2 (How Do Earth and Life Interact?), we focused on the biosphere as our home, and the fragility, interdependence, and complexity of the system.
DNA Structure
Next we jumped into the exciting discovery of the structure of DNA. We started with Part 5 of BFSU lesson B-27 (Units of Heredity to DNA) as an overview of the discovery. Then we tackled Real Biology 2 Chapter 7 (The Messenger) and the BHP lesson 5.3 (Ways of Knowing: Life) simultaneously for a couple of weeks. Building the marshmallow DNA model helped to bring to life the readings on Watson, Crick, & Franklin. We even isolated our own DNA in a microscope lab!
Investigation Essay
My kids really enjoyed this part so we skipped ahead to the BHP investigation essay next, while we had a lot of energy. I try to be intentional about providing an opportunity for the kids to wonder and practice critical thinking in each unit we study. For the investigation, they looked at how and why theories evolve. Starting with reading the 10 texts provided and using the three close reads strategy. Since these readings are often original scientific documents or articles and can be a bit dense, the kids skim them first for what they think the article will be about. We talk about how each fits into the bigger picture of what we are studying, so they can see where we are headed. Then they read the texts on their own, making notes in the margins. Finally, we read them together one more time, often creating a mind-map of what we learned (this comes in handy in the writing process later). The investigations are my favorite part of The Big History Project. We have a lot of discussion before the kids start writing, so have a rich set of ideas to draw on and the writing flows.
Cell Replication
I had intended to go deep on the process cells use to maintain the correct type and number of chromosomes, but we lost steam on the investigation and were ready to move on. So we skipped the Biology2 chapters on mitosis and meiosis and instead watched some youtube videos to make sure they were exposed to the ideas. (Links provided below.)
Inheritance
Then we studied genetic traits and inheritance using Chapter 10 of Biology 2. This was a fun way to review what we already knew about Mendel and play with inheritance of traits in the activity and lab projects.
I also skipped the lesson on how space collisions impact the universe in BHP 5.4 (Impacts!). While an interesting lesson, we ran out of time and I didn’t think that my highly-sensitive kids needed to dwell on the threat of future collisions or the general survival of our species. We explored the Chelyabinsk meteor strike last year in the Bravewriter Faltering Ownership mini report of a natural disaster, so I felt like we had that covered.
The Output:
Here are some of the BHP mind maps we created in discussion:
And here are the investigations my kids wrote:
More good stuff:
Some of my favorite extra resources from the library and online for this unit were:
Tree of Life interactive infographic
PBS Nova: Switching Genes On and Off (See also Nova episode on Cracking Your Genetic Code)
Bill Nye’s Genetics - Greatest Discoveries Documentary
The Double Helix: A Personal Account of the Discovery of the Structure of DNA by James Watson
The Usborne Introduction to Genes and DNA
The Stuff of Life: A Graphic Guide to Genetics and DNA by Mark Shultz
DNA Detective by Tanya Lloyd Kyi
Gregor Mendel: The Friar Who Grew Peas by Cheryl Bardoe (picture book worth a read)
If you really want to geek out on this:
I did not take Biology in school, so I was a little nervous about how this would work. But we had a great time and learned a lot - a win in my book. I hope that you find this information helpful as you play with ideas in your school. Have fun!
