Who Took Jerell’s iPod? -- An Organic Compound Mystery

Possible substitutes include sunflower seed butter, pumpkin seed butter, soy nut butter, and tahini (made from sesame seeds). If you are allowed to use nut butters, consider almond butter, pecan butter, etc. Additional information is available at https://www.foodsharkmarfa.com/peanut-butter-substitutes/ and https://www.thekitchn.com/5-nut-free-alternatives-to-peanut-butter-222921. If you do try one of these alternative butters, please pilot test it before using in your classroom. Also, please let us know how it works out, so we can include this information in our Teacher Preparation Notes.

Thank you,

Ingrid

I think that the procedure is likely to work alright with real egg whites instead of powdered egg whites, but I don't know and I strongly recommend that you pilot test this change. Note that you will need to include the egg white in the liquid evidence instead of the dry evidence (see Teacher Preparation Notes page 3).

If you omit the glucose, you will need to make multiple changes in the Student Handout and it may become difficult to make the mystery work out in a good way. You can purchase glucose as dextrose, so perhaps that will make it easier for you to include glucose as described in the Student Handout.

Ingrid

Thank you for your appreciation!

In the Student Handout on the bottom of page 5, the bottom two rows of the table refer to the dry and liquid evidence from the scene of the crime. On the third page of the Teacher Preparation Notes, the second table describes how to prepare the dry and liquid evidence, depending on which worker you want to identify as guilty of taking the iPod. (If you teach multiple classes, you may want to rotate who is guilty in different classes.)

Good luck!

Ingrid

I would suggest that, for each question or group of questions, you think about whether you want to use this question for:

    – writing answers that will be graded and discussed

    – writing answers that will be checked off and discussed, but not graded

    – writing answers that will be discussed, but not checked off or graded

    – discussion without necessarily writing answers.

For example, you might want to grade only questions 1-3 on page 4 of the Student Handout and questions 1-2 on pages 7-8.

Discussions of the questions as you work your way through the activity can serve as formative assessment and provide the opportunity to give constructive feedback to student responses and should also help to keep the students engaged. Grading the suggested questions could serve as summative assessment. I hope you can adapt this general approach to work well in your classroom. 

We are not sure why you are having trouble getting beans and yogurt to test positive for protein, but one possibility is that Biuret solution may become less sensitive over time, so we recommend using fresh Biuret solution. Gelatin tests positive for protein because it is a mixture of proteins and peptides derived from collagen, a protein that is abundant in bones, connective tissue and skin.

I will be happy to prepare more detailed teacher instructions after I finish my spring teaching. In the meantime, it will be helpful if you and others would let me know any questions you have, additional information you would like to have, or specific aspects of the instructions that you would like to have clarified.

Thanks,

Ingrid Waldron

For day 2, the students test the food items listed on page 5 of the Student Handout and the dry and liquid parts of Jerell’s evidence to complete the table on the bottom half of page 5 of the Student Handout.  To prepare the dry or solid evidence and the liquid evidence, consult the instructions on the top of page 2 of the Teacher Preparation Notes.  You can pick whichever worker you want to identify as the one who left the evidence.  For the dry or solid evidence, combine starch and protein for José’s lunch/snack or glucose and protein for Ashley's lunch/snack or glucose and starch for Bruce's lunch/snack or just starch for Kiara’s snack. Follow the instructions in the table to know whether to have the liquid evidence be oil or water. Then, have your students test the dry and liquid evidence samples for glucose, starch, protein and lipid.

You will notice that our Teacher Preparation Notes recommend having different evidence samples for different student groups to test, so different groups can't just assume they will get the same results as other groups.  However, if you prefer, it is fine to give all your groups the same dry and liquid evidence samples.

Please let me know if you have any additional questions,

Ingrid