Historical Connections: Ecology and Classification
Lesson 5 of 7
Objective: SWBAT to trace the schemes of classification by investigating the work of ecologist Robert Whittaker.
I use this brief chapter from the book Doing Biology by Joel B. Hagen to provide a broader historical context to our discussion about ecology and classification. Whittaker's work in connecting how organisms obtained nutrition and how that could be used to create a usable classification scheme is an interesting read that connects many different topics of study we have worked together on this year. I also like that it brings in a secondary text that allows us to practice close reading skills together. Many teachers choose to skip this type of lesson but I have found that my students retain and connect the many fields of biology in a much more substantive way and I attribute that in part to the work we do together to make those links explicit and to give them time to have conversations about them. You may have noticed that I include secondary text source lessons as part of each of our units in this biology class and although it does require more class time together to work through the material we are studying, the cumulative impact of this type of time and attention to reading comprehension, vocabulary building, and collaborative and individual reading strategies has been powerful as I measure their assessment writing skills and observe the complex nature of student driven projects I have received this year.
I also like this Whittaker story because it can flow into a bigger conversation about the many other ways to classify organisms and why you might choose one classification scheme over another, the idea that accuracy is only one piece of the puzzle and that whatever scheme you choose has to be functional/usable and match the goals of the area of study in question. Another secondary theme I like to bring up with students if they don't come to it on their own is that this is yet another story about a scientist working outside of his chosen field in a way that brought new perspective and insight that led to a lasting shift in thinking by scientists in that field. Watson and Crick are two other scientists that worked outside of their fields of expertise to create the most influential DNA discovery of their time! I believe it is always important to demonstrate to students how each one of us can contribute to discussions of big ideas from our own unique perspective in ways that can significantly impact our community understanding of those ideas. I have also used readings from this book to support student research projects about Lynn Margolis' endosymbiotic theory among others.
1. Tell students that today you will be investigating the history of how we classify living things. Pass out the Doing Biology reading and the Robert Whittaker and the Classification of Kingdoms guiding questions document.
2. Announce to students that they will be working with a partner to read, annotate, discuss, and answer the questions about the ways in which classification of organisms shifted over time.
- Note: See this previous close reading annotation student work sample document to show some of the ways that students might annotate their reading for understanding. On page two of this document, you will find the annotation strategy tips sheet my students and I have been using throughout the school year.
3. Ask students to group themselves with a reading partner and find a place in the room to get settled. Assist any students that seem lost or unsure about partner choices.
- Note: At this point in the school year, this is typically not an issue as students have a clear sense of who they work well with and who they would be able to have meaningful conversations with in order to learn about the material.
2. Allow students time and a quiet space so that they can read, annotate, and reflect upon their chosen article.
- Note: For support, students have the option of reading on their own or with a partner. For specific groups, we may read out loud together or the group may choose to lead that activity on their own without my facilitation. Our classroom is large and has two side office spaces and an outdoor space with multiple benches to allow for this additional support. Depending upon your set up, you may want to move to the library or another space to allow for multiple student groupings and interventions.
- To support students with their annotations, I always have post it notes, highlighters, and other classroom supplies available for students to use. I often put on classical music while they are reading and annotating and I allow students to work together, alone, or with me in various areas of the classroom as needed.
- For a more in depth look at annotation strategies, check out this example resource.
3. I do not collect student annotation notes; my philosophy is that those are for them to have and refer to as needed. The assessment piece for me is their guiding questions document, which they create with their partner and turn into me for grading later on in the week.
1. Ask students to get into groups of four (two pairs of reading partners) and consider the following prompts:
What sticks out to in this reading you as interesting or important?
What ideas need further review or clarification?
Do you agree that an ecology based classification system is the best one to use or is there another way you think we should be organizing living things in categories?
2. Use the spokesperson protocol to share out group responses.
3. Draw out a summary diagram of our tree of life. See my whiteboard drawing for ideas. Students will be very interested to see how it has shifted, not only from the 2-6 kingdom classification scheme they read about in their article, but also in our newer understanding of the relationship between archeabacteria, (eu)bacteria, and all of the eukaryotes. This step really helps students link together their prior knowledge to this newer exploration of classification, taxonomy, and phylogeny.
- Note: The discussions my students and I have had revolve around the comparison between what scientists used to think about our phylogenic/taxonomic family tree over time versus our newer understanding of how life has evolved across geologic time. Students will ask what changed our ideas and the answer, as is often the case, is related to technological breakthroughs. As we create better tools for examining structures, we can compare them more accurately and completely and that is what happened here to show us the strong connections between our most ancient organisms, the archaebacteria and all modern eukaryotes.
4. Address any clarifying questions before the period ends. Remind students of their guiding questions document deadline.
- Note: See the guiding questions document answer key for support with guiding questions responses. Typically, students will want to hear you briefly address/discuss the way that the classification framework shifted (plants and animals-->bacteria, plants, animals, fungus-->addition of protists-->break up of monera into eubacteria and archaebacteria). Discussing the protist kingdom is important! The idea that it is the only kingdom that is joined more by what things are not rather than what they are (none of its members quite fit into the other eukaryotic kingdom frameworks based on ecology or structure), the dividing line between prokaryotic monera and eukaryotic everything else, and the break up of the monera kingdom into two distinct types of bacteria is key to their broader understanding of classification and ecology. These conversations can start during this session as students complete their reading and can continue when they turn in their joint work later in the week.