Teaching Quantitative Skills using the Floating Disk Catalase Lab: Intro

I find it remarkable how deeply the biology education community has embraced the call to increase quantitative skills in biology.   This is certainly not an easy change to incorporate into our curricula and it is one that the community will be working on, tweaking and improving over time as our own instructional quantitative strategies and skills mature.  But even with this willing effort by the community where does one find the time to add “something else” to an already packed curriculum?   The first part of the answer to that question is to first have confidence that it can be done;  the second part of the answer has to do with strategic and efficient curriculum decisions; and the third part of that answer is to realize that, like our students, we are somewhere on learning progressions ourselves and that our skills and understandings will deepen the more we teach quantitative skills.  No one has time to teach all the biology they would like to teach.  Every year most of us make all sorts of decisions about what to include, what to emphasize, and what to leave out.  The challenge of adding structured instruction in quantitative skills is daunting, particularly since most of us have not had time to develop our own math-based pedagogical tools and skills.  With that in mind we often fall back on the type of math instruction that we likely encountered in our own educational background.  If, like me, most of your math instruction was based on algorithms and focused on getting answers instead of learning how to do math, then likely if we model our quantitative skill instruction on the math instruction we experienced, we won’t be doing a very good job helping our students develop quantitative skills.  Instead, perhaps we (the biology teaching community) should consider delivering quantitative skills instruction in a way that models effective and efficient math instruction informed by research.  Here’s the good thing–it turns out that many of the strategies that work well for teaching science also work well for teaching math.  We biology teachers just need a bit more experience trying to explicitly teach appropriate quantitative skills.  We need to develop our own specialized pedagogical content knowledge.   I thought I’d put out an example of how this might work in a classroom–certainly not as an exemplar but more as a starting point.

To this end, at the 2016 NABT meeting Jennifer Pfannerstil, Stacey Kiser and I shared strategies to introduce quantitative skills focused around a classic lab: The Floating Disk Catalase lab.  The earliest version of this lab that I know of was published in ABLE.
A Quantitative Enzyme Study Using Simple Equipment by Beth A. D. Nichols and Linda B. Cholewiak.   Yes, that is the same Beth Nichols that recently retired from ETS but has worked with so many in this community.

In this series of posts I’ll walk through the material we presented at NABT along with some discussion on the rationale of each example coupled with resources so that you should be able to design your own lab that structures quantitative skills.  A caveat:  I want to emphasize how rich this particular lab is for developing quantitative skills–in fact I’ll present more possible ideas than probably anyone will want to use in any particular class.  So pick and choose what works for you and your class but consider the examples presented here as something to shoot for with your students.  Let’s get started.

Lab Overview:  

If you are not familiar with the lab it features a simple and student friendly method to measure/quantify enzyme action or kinetics using disks of filter paper soaked in a yeast solution as the enzyme source and a solution of hydrogen peroxide as the substrate.  Here’s a right up by Paula Donham on the technique:  http://www.kabt.org/wp-content/uploads/2009/02/catalase-enzyme-lab.pdf  Note that one of the educational goals that Paula used this lab for was to introduce the use of box plots as a way of presenting your data.  (That’s a quantitative skill, btw.)
The materials:
How does it work?
Dip the paper disk in the yeast solution.  The yeast solution provides a set amount of catalase per disk.  Drop the disk into a solution of hydrogen peroxide.

The catalase breaks down the hydrogen peroxide into water and oxygen.  The oxygen bubbles catch in the paper fibers and eventually cause the disk to rise. You can see the disk staring to rise in the lower right hand corner of the cup.

I use the plastic cups to make a dilution series with the hydrogen peroxide and the 24 well plates for the testing.  The well plates allow you to put one disk per well (which might lead to better precision).
Ready to collect data with eight data points per substrate dilution:
Here’s a short video of the procedure using the well plate:
Dip a disk in the yeast, drop it into the hydrogen peroxide and time how long it takes to rise.
Why use this lab for introducing quantitative skills?
The simplicity and precision of this lab technique allows the teacher and the class to more deeply explore concepts about enzymes but also to explore how different quantitative skills can provide a path to even deeper understanding.  The key here is that the technique is so simple, the students can concentrate on thinking about what is going on with the enzyme, how to capture that quantitatively and how to support their conclusions with data.  And, they can simply do it over if errors are made since it takes a small amount of time.  There are some other aspects of this lab that allows you to introduce different approaches and deeper understanding as you build quantitative skills.  In my classes, I had three main goals for this lab:  1.  To begin an understanding of enzymes and enzyme action; 2.  Introduce and practice a number of quantitative skills (including serial dilutions and graphing);  and 3 Introduce and practice experimental design and scientific argumentation.  In my classes, we would introduce the technique, let everyone in the class practice it,  and then assign the actual data collection as homework.  The students had to acquire their own materials at home, collect the data and report back to class.  They could work collaboratively or with their families.  The lab is safe, inexpensive and doable.  By assigning the data collection as homework, this freed up class time to work on the quantitative skills.   The students generated mini-posters to share their work with their peers.  In the next post I’ll talk more about how you might present this lab to students and the types of quantitative skills you can build and practice.

Model Building and Building on Models

I make my students build and use models on a daily basis in my classrooms. I think that I have a better than average grasp on the Next Generation Science Standards, their practice and three-dimensional lesson planning. But I have apparently never thought to throw a bunch of vocabulary words at my students and give them the time to really struggle to connect them into a cohesive model with their groups.  And at the end of a session on Cognitive Models, presented by AP/IB Biology teachers Lee Ferguson and Ryan Reardon, that is exactly what we did.


To start, the instructions were sparse: Create connections and uncover relationships between pancreatic β-cells and photosynthesis. My group was made up of six other AP Biology teachers from 4 states, none of us with any idea where to start. There was some discussion about the significance of the color of each card, which it ends up wasn’t important… there just wasn’t time to sort them before the session.  We eventually found the word “Metabolism”, which we all agreed was the one thing that all the cards shared. From there, we tried to make shorter stacks of cards that were related. For example, “Hyperglycemia”, “Blood sugar rises”, and “insulin”.

Once we had all the cards grouped, we tried to place them into a pseudo-concept map. In our classrooms, I would have probably done this on a big whiteboard so we could draw arrows and write connecting terms, but my group guess that the Sheridan didn’t want us writing on their table cloths. 🙂  As we went, we had to stop and rearrange our map several times and each time we edited the map, members of the group were justifying why some cards had to stay or move.  It was a really great conversation and I learned some things about feedback loops that I don’t think I had ever known.

At the end of the process, we were encouraged to go look at what the other tables had put together and reflect on our map. To my surprise, none of the other groups had anything resembling our model. Talking to some of the other groups, I don’t think that anyone had a model that I think failed to achieve the original objective. It was really a powerful reminder that students, no matter the amount of information they may possess, each approach a problem from a unique viewpoint. And when you have people put together information, even people that all know “the right answer”, there are many ways to arrive at that conclusion.

Needless to say, next week when we start preparing for our next test in my 9th grade Biology class, my students are getting a stack of 3×5 cards tossed on to their tables. I can’t wait to hear their conversations and see what they create!

This post is part of a series of posts from KABT members reflecting on some of the most important things they’ll bring back into their classrooms from the NABT 2016 Professional Development Conference.

ECET2 Take-Aways

This weekend I went to the Elevating and Celebrating Effective Teaching and Teachers in Kansas Conference. That is the longest name for a conference ever, so I had high expectations. Drew invited me to share anything of value I received, and while the conference didn’t blow me away, it did encourage me to take care of myself, and that was much needed.

Here’s a jumbled list of important takeaways:

  1. One of the important things we often forget is to take care of YOU!! Think Maslow’s hierarchy – you can’t efficiently teach your kids when you aren’t well yourself. The metaphor I heard was to take on tasks like cleaning your closet. If you add something, take something away. This is ridiculously simple, and caused me to create a list of 3 things I could drop so I could become a better teacher and wife. Basically, instead of doing more things half-assed, do a few things really well.
  2. A wonderful student from Washburn Rural High School gave a speech over how important educators have been in her life. Just remember that you often impact kids in ways you may never be aware of! Favorite quote from her talk, “You are not just teacher. You never were just teachers. You are future-makers.”
  3. You don’t have to get a Yeti brand water bottle, a lot of the knockoffs are just as good.
  4. After moving to a totally project-based learning curriculum, I have been struggling trying to keep up with grading, so I made it a goal at the conference to learn about a way to make it more efficient. Tomorrow I plan to invite students to meet with me one-on-one in the mornings or after school about a grade if they want to see it graded sooner. This will not only make my grading pile smaller, but it will also allow me to discuss my grading expectations and give time for them to reflect. I’m still looking for ways to design the projects with less… grading, so ideas welcome there!

Enjoy what’s left of the semester! I’ll try and come back here soon with a post on case studies, or Pokemon! 

  • Jessica Popescu, Seaman High School
  • @MrsPopescuSHS
  • jpopescu@usd345.com

NABT 2016 Notes

20161105_085707Last week, biology teachers from around the country (and Canada) descended upon Denver, CO for the annual NABT Professional Development Conference. KABT members and Kansas teachers were particularly well represented with 17 Kansas educators (yes, we have claimed Camden and Vivian) in attendance! A hearty thanks to Camden Hanzlick-Burton for providing us with a GoogleDoc to aggregate our notes into one collective document.

You can access this document using THIS LINK. If there are any questions about the document, feel free to contact me.