Identifying Organic Compounds in the Lab (Day 4 of 5)

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Objective

Students will be able to identify proteins, carbohydrates, saccharides, and lipids in the lab.

Big Idea

Get your students acquainted with organic compounds in their everyday lives using this engaging lab activity!

Notes for the Teacher

Every biology class utilizes an organic compound identification lab;  for me, this is one of the best.  By slowing down to introduce the lab equipment and safety as a separate lesson rather than a quick reminder at the start of the lab procure day, we engage student curiosity and allow them to fully digest the many complex test procedures they will be following.  

Adding in a student choice day engages students and makes things more personal for them which creates a very positive, collaborative, and inquiry based lesson day where we work together to figure out how to work with our diverse samples and asses the accuracy of our results.  And finally, giving students an opportunity to share out their original data as a class allows them to critically compare and analyze data against their prior knowledge and come up with interesting questions they'd like to investigate in the future.

The lab is broken up into a five day series:

During Day 1, students complete a pre-lab activity and explore the equipment, procedures, and safety guidelines for the series. Standards: W.9-10.1, SL.9-10.1, SP1, SP3, SP4, SP8, XC-SF-HS-2

On Day 2, students focus on the lipid and saccharide tests for five samples.  Standards: SL.9-10.1, SP1, SP3, SP4, SP8, XC-SF-HS-2

During Day 3, students focus on the protein and starch tests for five samples and brainstorm their own group samples to bring in for testing.  Standards: SL.9-10.1, SP1, SP3, SP4, SP8, XC-SF-HS-2 

During Day 4, student groups work to test their own five samples.  Standards: SL.9-10.1, SP1, SP3, SP4, SP8, XC-SF-HS-2 

And on Day 5, we come back together as a large group to assess our lab work results and review the major concepts of the series.  Standards: W.9-10.1, SL.9-10.1, SP1, SP3, SP4, SP8, XC-SF-HS-2

The Classroom Flow: Student-Designed Explorations

45 minutes

1.  Ask students to take out their lab document and turn to page three for lab procedures that they will be working with again today.  Show the standard lab set up they have been working with at their lab tables each day of the lesson series so far one more time to prepare them for their task today.  

2.  Tell students that today they will be testing the substances their group has chosen for analysis in the four areas we have worked with:  saccharide, starch, lipid, and protein tests.  They will be recording their data on their additional lab data sheet where they made predictions yesterday for each of the substances their group chose for testing today.  

3.  Remind students about reagent safety and allow them to get to work.  By this point, students have had three solid days of working with the lab procedures and materials and they will be very familiar with the safety guidelines and how to connect their data to broader organic chemistry concepts (Check out the organic chemistry lab tips and tricks sheet for ideas about the ways you can best support your students with basic lab techniques and safety).  I found that the support students really needed during this session focused on the following three areas:  

  • How to prepare their samples:  Do they need to dilute the thickness of the Nutella they brought in?  Should they grind up their granola?  How much water should they add?  These are the types of questions I asked and when students wanted to pursue specific ways of working with their materials, I was ready with extra containers and specialized equipment such as a mortar and pestle.
  • How to analyze their test results when colors are an issue: For me, this involved a lot of questioning and encouragement for students to trust their judgement and compare with other groups encountering similar challenges.  In real science, there isn't one person who confirms or denies a scientists' work and I didn't want them to come to me as the expert on their materials.  Because I had the sign  up document, I was able to connect groups that might be able to help each other.  Sometimes, students wanted to see the list to find out if a group later on during the day might have a similar ingredient so that they could share results on their own or through me.  It was pretty great to see their curiosity expand out in this way across every class period.
  • Encouraging students in their own process as a team:  I found that my main job for this new day of our organic chemistry lab was to be a cheerleader for teams--they took a lot of pride in working with unusual ingredients and choosing things they were really curious about and that they wanted to explore further.    

4.  Overall, I found no issues with student behavior during this session.  Because they are completing all four tests for their four samples (rather than spreading this out over two days as we did for the initial testing experience), they have plenty to do and at the same time, they are familiar with the testing procedures due to the scaffolding of the previous days.  The energy in the room was positive and excited because students had chosen things they were really interested in learning about through our lab tests.  I had kept a few emergency samples ready in case a student group had forgotten to bring their materials but that did not happen during any of my class periods for the day.  For more about teacher and student preparations for this session, check out my reflection section from Day 3 of the lesson series.  

5.  The student work sample shows some examples of the types of substances student groups chose to investigate during the student choice lab day.  This group was later able to accurately address some of the discrepancies between their hypotheses and data (for example, their hypothesis for chili powder carbohydrate content and their data for the lipid test for chili powder)in their formal lab write up document due after Day 5.   

The Classroom: Clean Up and Check in

5 minutes

1.  Remind students about our clean up norms:  leave lab tables and materials in the same way that you found them:  neat, organized, clean and dry.  

  • Note:  At this point in the year, this process should run smoothly.  I typically take on an active role at each lab table to ensure that clean up is taken care of by each group.  I do this with gentle and specific reminders of tasks left to complete for each of the eight lab groups.  Tables are numbered and I will not dismiss a class if tables are not ready for the incoming class.  The best thing I can do to support appropriate clean up is to begin announcing that the process should be in motion about ten minutes before the bell.

2.  Announce that student groups will be sharing out their lab results tomorrow with the class.  Tell students that they will have time to complete any remaining tests and collaborate before presenting.

  • Note:  The tests are quite short and most groups will be finished.  There may be a few groups that want to retest something.  I check in with each group and determine what time frame is appropriate--if they want to redo a test involving a water bath, we discuss arrangements for group members to come in at lunch or after school.  If it is a more simple protein or starch test, it can be completed during the first ten minutes of class as students prepare to present their results.  I found that students were eager to find out the information they were looking to confirm!

Now on to our final day, Day 5!