Enzyme Function: Exploring the Concept of Denaturation with Pineapples (Day 2 or 2)
Lesson 7 of 15
Objective: Students will be able to collect and analyze data in this classic enzyme denaturation experiment. Big Idea Get your students thinking about enzyme function and all the ways it can be affected in this classic pineapple lab!
This lesson series explores enzyme activity using a classic bromelin/pineapple set up. On Day 1, students perform the lab procedure and document their data. On Day 2, we work together as a class to analyze our results and summarize our findings. I like this experiment because it isn't an easy reach for students conceptually and our collaborative conversation requires focus and close attention by the students in order to follow the data to its conclusion. Anytime we get to practice this skill at a high level in class, I am very happy to do!
You will notice that the first day of the lab is very student centered--the directions for the lab procedure are explicit and easy for them to follow, allowing you time to monitor for safety and materials handling, as well as observe how individual groups are working together as a team and intervening/supporting as necessary. The second day of the lab is when you as the teacher direct the flow of discussion that enables deeper understanding and connection by the students, linking the concept of enzymes and how they work within specific temperature and other parameters.
For me, I am finding that enzymatic action is something that we revisit throughout the year and each time, student depth of comprehension grows. This is the first activity in that spiral of conceptual understanding. I like that the first day involves easy technique that students enjoy engaging in with everyday materials like pineapple that look and smell good. That may sound silly, but anything the connects science to student life, experiences, and strengths is a subtle strategy I intentionally employ in order to get each student to consider science as something relatable, doable, and relevant to them as people and citizens.
1. Ask students to take out their enzyme denaturation lab document from yesterday's experiment.
2. If students need to check their samples for the first or second time (depending on if you used ice baths, the refrigerator, or both), allow them time to do so. Tell students to check in with their group to confirm their data and conclusions and prepare for our group discussion by agreeing upon collective questions or ideas to share.
- Note: This loose structure at the start of the class is atypical for me but it fits here. Students want to finish their work, they know what they need to do, and the sooner they finish, the faster we can get to our group discussion and students will be quick to tell me they have questions and want to get to that as soon as they can! The energy will be busy, but not chaotic and I stay available for questions, most of which will center on logistics and supplies, including "I can't find my..." "Where do I find the..."
3. Just in case you have any absent students wanting to make up the lab during this time, have the lab supplies set up and available. If the room and equipment will be out for student use at other times during the week outside of class sessions, announce that information.
1. Start the conversation about lab data by reviewing the basic actions of enzymes and the specific action of the enzyme in this experiment, bromelin. See my enzyme and bromelin action boardwork for the information most relevant to this discussion today.
2. Now that students have a better understanding about the work of bromelin will affect the gelatin, now it is time to set up what they think should have happened to each sample. Using an open question and answer strategy, write out the ideal/predicted outcomes on the board.
- Note: This lab is one that looks deceptively easy at first but the more you work with the data, concepts, and student responses, you realize it requires a lot of unpacking and when I do that, the results are meaningful for kids way beyond this unit. The conversation we have together at the beginning of this lesson is critical for meaningful data analysis in the next step. Although I typically use a more formal question and answer protocol for group discussions, here, I want to keep the structure more relaxed, taking what information students can give me and shaping it into a narrative about enzymes that connects to our lab work over the past two days. The more formal, student driven discussion step will happen in the next section of the activity.
3. This is the time to revisit/reteach the concept of denaturation that preceded this lesson series. Spending time on this step to connect the broader concept with the specific lab procedures and results will make the rest of the day's conversation go very smoothly. Using a short video clip can help support the conversation and prompt clarifying questions.
- Note: I structure this conversation by focusing on denaturation and how tempurature would impact gelatin: intact or denatured? I then connect it to our lab procedure/samples (canned, boiled, frozen, fresh). I also made sure to emphasize/question kids about the tube containing only gelatin (no pineapple), which served as a control for the experiment to ensure they remember what the function of a control tube does in this experiment
1. Ask student groups to compare their data to the ideal data chart and briefly discuss any disparities by asking:
Does your data match our predicted/ideal data?
You will see heads shaking left and right to tell you that no, their data doesn't line up. Smile and tell them that is ok, not to change anything on their data record sheet and that today is all about figuring out why that may be the case.
2. Using the spokesperson protocol, have each group share out their data and note any disparities/class trends.
- Note: I do this by creating a simple chart of the board next to my ideal data notes. See my class data board work for a better picture of what this informal collective class chart looks like.
3. From here, you can address any errors/issues and brainstorm reasons why they might have happened. In this class, there were a few issues with the control and 2 of the other samples. Some of what we came up using our spokesperson protocol to answer the following prompt included:
Why didn't our experimental results match the idea/expected results? What might have happened?
- misreading condensation on the top of the gelatin in the tubes as not being solid
- not waiting long enough with the ice baths to truly determine solidity of the gelatin
- and not cutting up the pineapple small enough/stirring it in the tube so that all of the gelatin had contact with the enzyme in the pineapple.
3. As a last review/check in of the data, I asked student groups to discuss their data and conclusion/analysis questions on their lab document and using the spokesperson protocol again, I ask students to share out one burning question to ask me/the class. Students will tend to want to go over the definition of denaturation and how the process of canning works. This first question is important while the details of the second one are not. I tend to ask them what their data tells them about the process of canning and they will be able to answer that there must be heat involved since the enzyme didn't do its job and liquefy the gelatin.
- Note: This 'burning question' strategy works really well in terms of directing class discussion and going over work in which some students might check out or have difficulty keeping up or staying engaged. Student groups feel confident asking their question because they've vetted it with their group and the process of picking one thing to ask the group/me requires that they focus on the big picture and the major concepts rather than very small details. Hearing other groups have similar questions is reassuring to students and gives me a great formative assessment tool as I determine areas to reteach.
1. At this point, students will have a much better understanding about the purpose of the lab, the connection between enzyme function and this specific enzyme and substrate (bromelin and gelatin), and the potential reasons for any data discrepancies between the groups.
2. Tell students that in addition to their lab data and analysis document, they will also be creating a conclusion paragraph summarizing their experimental results, analyzing their data, and conducting an error analysis of their experimental procedure and results.
- Note: At this point, we are still working on building these skills. As the year progresses, we will incorporate a more formal rubric but for now, answering these three essential points is my focus.
3. As you can see from this typical student work sample, content knowledge and experimental connections are strong throughout the writing. Students were able to refer back to our data, compare to the ideal outcomes, and tie back in to concepts related to denaturation and lab techniques for a controlled experiment.
- Note: This was by far my most successful iteration of this lab. By adding a full day for discussion, my students and I were able to make deeper connections between theoretical concepts, data predictions, and the investigative/inquiry process.