For the original activity please see Chi Klein’s post here: http://hybridteareflections.tumblr.com/post/73374338866/trouble-with-lagging-strands

I enjoy the “invisible” parts of Biology – the enzyme cascades and processes that underpin many of the macroscopic changes we can observe. It is maybe for this reason that I was originally drawn to molecular biology, and why the Cell Cycle and Genetics pieces of Biology 067 are my favorites.

The challenge, of course, is that these processes are invisible and happen on time scales that we cannot observe as a class. So, when I started planning my lesson on DNA Replication I really wanted something to help make it “real” and visible.

I found the “Trouble with “Lagging Strands”” Activity (linked above) and immediately felt a resonance with the goals I had in mind. Although this activity does contain some additional details my students did not need to know, I thought it would be relatively easy to adapt and provide a good summary activity for my students.

Iteration #1

The first thing I did was to create a summary sheet for my students: DNA Replication Summary Handout. I wanted to make sure they had some kind of take-away from the activity so they knew what parts were important. We started this concept as part of our online day – students should have watched a detailed video about DNA structure and replication (DNA Structure and Replication: Crash Course Biology #10 from CrashCourse) followed by a few review multiple choice questions using the TED ED Lesson Creator. In class the following day, we watched a shorter animation of the processes (DNA replication – 3D from yourgenome) and jumped right into the activity.

I walked the students through the steps, and asked them to follow along the process a second time together. This immediately drew the attention to me as the person who controls the process, and the second walk through of the process fell very flat. The students struggled to fill in their worksheets, and after reviewing them turned into a lecture. Although some students did say they enjoyed getting to “walk through” the process, I felt like the activity wasn’t utilized to its full potential.

Iteration #2

For this iteration I kept the same summary sheets I had created the first time. Unlike the last time, the students did not get exposed to this information in the online day, due in large part to scheduling. We began this lesson with a review of DNA structure and the cell cycle (which they had learned previous days). After that, we watched the same short animation as the first iteration. This time I directed students to pay attention to steps in the process and not worry about the names of each enzyme yet.

After the video, we did a short lecture on DNA replication, referencing the video to remind us of the visuals and giving attention to the important enzyme names. After that, we launched into the activity to “Try it!” (inspired by Bill Nye the Science Guy).

For this iteration I set the ground rules (which parts of the foot were 5′ and 3′, where the nucleotides were). After that, I asked for help remembering all the parts we needed folks to play. Some students would call out an enzyme, and then encourage someone to volunteer to be that enzyme. I kept asking “do we have everyone we need?” until students confidently answered “yes”.

After that, I used a series of questions to get students who did not volunteer to be enzymes to direct those who did on the correct steps to follow. This way each step was a group decision, and there was less pressure on the volunteers when something seemed “off”. We had a great learning moment when a student playing DNA Polymerase laying down paper nucleotides said aloud “Oh wait, that should be a “T” not an “A”.” I paused the activity and we discussed together how the student had illustrated a key job of DNA Polymerase and why certain bases join to others.

This version took longer (20 minutes compared to 10), but the students seemed to retain the details much better. They were able to collaborative fill out their summary charts with very little help and reviewing it was much quicker. The students reviewed this information in the next online day.

Final Thoughts

In hindsight, it is clear the first iteration was too teacher-driven and didn’t require the students to engage with the process enough. The second iteration gave students more agency, although we had a few uncomfortable moments where students were silent and waiting for direction.

These iterations were a good example of how letting go of some control lead to a better experience for students. I have thought back on this activity often when playing other activities or trying to find new ones. I try to ask myself “How much direction do the students really need?” and keep it to a minimum. I also write myself notes (along with facilitation notes and timing suggestions) to remind myself to ask more questions instead of answering right away. Often the other students can help put together a better understanding together then if I had simply provided an answer they did not feel the need to question.