Using Self-Explanation in an Introductory Biology Lab

Students working in a laboratory are looking at samples under a microscope and writing in a notebook

Contributed by Maria Valadez Ingersoll, Ph.D student at BU URBAN Program

(4 minute read)

In a previous post, we introduced the idea of self-explanation as a skill to promote learning fundamental principles behind a task to deepen contextualized understanding and strengthen knowledge transfer to new scenarios. To refresh, while a student is learning something new, they may break the concept into steps and practice self-explanation by answering questions such as: What is my goal for this step? What are the principles that I have learned that apply to this step? Are there any exceptions that can be made in this scenario? How exactly am I going to move to the next step? In today’s post, we are going to discuss how to implement self-explanation in a biology laboratory to enable students to apply theories they have learned in lecture to the living biological world.

Science, engineering, and technology laboratories provide hands-on approaches to learning that, if done correctly, allow students to contextualize what they are learning in lectures or textbooks into real world scenarios they can touch, see, and manipulate themselves. As a graduate student of biology and frequent educator of biology laboratories, I have performed and facilitated countless experiments that have both succeeded and – more often than not –  failed. When I was an undergraduate student doing my first experiments in introductory biology, I followed the instructions provided, but often did not understand what each step was doing to bring me closer to my final product. Thus, I was not actually applying my knowledge of biology to the task at hand and, if my experiment didn’t work, it was difficult to understand why, and nearly impossible to improve my experimental design. Additionally, I was unable to transfer knowledge from one protocol to investigate a new scenario. When I began explaining to myself what each step of a protocol or method accomplished at the biological level, my success rate improved, and I was able to ask, and answer, more intricate research questions. But how do we encourage all of our students to practice self-explanation as they work through a laboratory experiment?

In all biology laboratories I have taken and I have taught, it is required that students read through the protocol before arriving to lab. However, a simple read through is often not enough for students to understand each step of a protocol. The following example is a task that students should complete before coming to lab. During the first few minutes, students can discuss their answers with their lab partner and then individual students can be called upon to share their answers with the class. This task will encourage students to reflect on the protocol and explain to themselves and their classmates the biological processes accomplished by each step. This example can be adapted to many protocols across the STEM disciplines and may be used in laboratory learning environments or may help you in your own research!

____________________________

Make sure to have read the lab and completed this task before coming to class! The boxes below have critical steps you will need to follow today during Week 1 of DNA Extraction and PCR. 

  • In the empty boxes to the right, fill in the biological processes you learned in lecture and in the pre-lab that explain what the step is accomplishing. 
  • When you come to lab, you will discuss your answers with your neighbor!
PROTOCOL STEP EXPLANATION
Combine 50 uL of DNA lysis solution with a small amount of ground sample Example answer: DNA is in the nucleus of cells. In order to extract the DNA, we have to break open the cells (that have cell membranes and sometimes cell walls) and the nuclear membranes using detergents and enzymes in the lysis buffer.  
Incubate sample+lysis solution for 10 min at 95degC Hint: think about optimal temperatures of reactions and the properties of cell membranes
Remove tubes from heat and, at room temperature, add 5 uL of DNA Neutralization solution; mix thoroughly
To a new tube, add the following reagents for the PCR reaction:

  • 20 uL PCR primers
  • 5 uL PCR mix containing Taq DNA Polymerase and dNTPs
  • 5 uL template DNA 
What does each reagent provide to the reaction?
Run 35 cycles of the PCR program

  • Denaturation at 94deg C
  • Annealing at 55deg C
  • Extension at 72deg C
  • Repeat 35X
What is each step doing to the template?