Pineapple Enzyme Lab (Day #3 of 3)

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Collect evidence and use it to develop a claim and compose an argument about the effect of temperature on enzyme activity.

Big Idea

Enzymes are protein-based molecules that catalyze (speed up) chemical reactions. Cell chemistry is essentially impossible without sufficient quantities of properly working enzymes.

Learner Goals

Note: I recommend that you first check out this resource in order to get the most out of this lesson!

In high school I took several drafting classes and, for a while, I had hoped to become an architect. With respect to planning instruction and teaching, I feel that I can still live out the detailed approach to building something intricate and complex even though the product is a lesson rather than a certain "built environment".

The lesson-planning document that I uploaded to this section is a comprehensive overview of how I approach lesson planning. This template includes the "Big Three" aspects of the NGSS standards: Disciplinary Core Ideas, Crosscutting Concepts, and Science Practices. Of course, there are many other worthy learning goals, skills, instructional strategies, and assessments that can be integrated into a class session. I don't feel compelled to check every box but, rather, use it as a guide to consider various options and tailor the lesson in light of these.

With regard to this particular lesson, students will be able to:

Collect evidence and use it to develop a claim and compose an argument about the effect of various temperature conditions on enzyme activity.

I hope you get some value from my work!

Anticipatory Set ("Hook")

10 minutes

Continued from Day #2...

Collecting Evidence:

To start off class, I discuss with the student teams what they might conclude about the activity level of the pineapple enzyme (based on the condition of the gelatin observed in  today's big reveal). Essentially, what will be the appropriate pairing of claim, evidence, and lines of reasoning for this lab? Typically there are three outcomes:

Option #1: If the gelatin is solid after refrigeration when mixed with the temperature-treated bromelin enzyme, then the enzyme is not working properly because it has been denatured. The control beaker will contain solidified gelatin without any enzyme contact therefore this reasons that the enzyme must be ineffective post-temperature treatment.

Option #2: If the gelatin is liquid after refrigeration when mixed with the temperature-treated bromelin enzyme, then the enzyme is working properly because it has not been denatured. The reasoning here is that the enzyme interfered with the normal course of events in making solid gelatin.

Option #3: If the gelatin is partially liquid and partially solid (what I call "sliquid)" after refrigeration with the temperature-treated bromelin enzyme, then the enzyme is working working only partially properly because it the enzyme has been slowed down (decreased kinetic energy leads to partial activity).


Instructional Input/Student Activities

20 minutes

Carry out the Plan: Refer to "Procedures" written and carried out by students in the Bromelin Lab Investigation document.

Students are prompted to carefully observe and record data according to their plan and complete the "Data and Observations" section of the lab template. As they do so, I circulate and check in with teams to determine:

1. What evidence have they collected (condition of gelatin in both of their beakers)?

2. What claim have they determined is most appropriate? In other words, is their enzyme fully active, partially active, or fully inactive?

3. What is the most reasonable explanation for #1 and #2 above? This gets at the conditions that potentially impact the behavior of the enzyme.

Clean up: Disposal of lab products (gelatin, pineapple puree) should be made into the trash bin since I don't want my lab drains clogged. Students should also practice good lab citizenship by washing and storing of glassware. Heck, I don't want to do it and its all part of owning the experience, right?

Class Discussion: Back to your seats when done!

Closure: What did we learn? Where do we go from here?

25 minutes

Teaching Challenge: How do I support my students to compose, communicate, and evaluate a clearly stated, evidence-based, compelling argument?

Teaching Challenge: How do I support my students in analyzing data in order to address a question of interest?

Hmmm...good questions! Here goes my response!

Data Analysis and Communicating Scientific Thinking:

Using the class Bromelin Lab Data table, I prompt students to share out their data (from Groups #1-8) and record it in the Excel form (projected on the classroom screen) for all to see. Quickly, students see the trends among and between all groups.

From here, students are guided toward making a claim about the effect of temperature on enzyme activity, citing evidence, then explaining the reason (rule) that an enzyme might work properly or not. This follows the “Claim-Evidence-Reasoning” (CER) model used by many teachers. For example a student might conclude:

Claim: Elevated temperatures (~40 C) cause the Bromelin enzyme to become ineffective.

Evidence: When heated to the elevated temperature and mixed with liquid gelatin and refrigerated for 24 hours, the gelatin turned solid.

Reasoning: Normally, active bromelin will prevent the gelatin from solidifying under those conditions. in this case, it didn't therefore the elevated temperature must have changed the structure of the enzyme (denaturation) which caused it to fail.

Independent Work: Students ought to complete the entire Lab Handout by the next class period.

Lesson Extension & Follow-Up Activities

Homework: Students will complete the Lab Report Peer Evaluation form. In doing so, they will thoughtfully evaluate their peers; a useful lens of feedback to me about each members' participation. This is an accountability measure related to students participating fully and equally; a necessary component to trusting that each team member has the other members’ backs. This, in conjunction with what I see, will serve to evaluate student participation.