Protein in Foods
Lesson 6 of 11
Objective: SWBAT identify foods and liquids which contain protein.
Because my students tend to know a lot about protein, I begin the lesson by asking my students to share what they already know using the protein KWL. I ask students to think about what they already know about protein and to record their ideas in the "K"(know) section of that chart. Next, I ask students to think about what they would like to learn about protein. I tell students that this is their opportunity to ask questions about things they are curious about. After students record their questions in the "W"(want to know) section, I ask students to share their charts with their science groups. This activity is beneficial because it activates student prior knowledge and uncovers misconceptions. I purposefully do not correct any students misconceptions until the end of the lesson. This strategy allows students to conduct the lab and refine their own thinking prior to any teacher corrections.
The procedures in the protein test lab differ greatly from those in the other labs in this unit. Because of these difference, I provide a lot of instruction to students prior to the lab to ensure that all students can successfully complete the lab. In this lab, students will use both test strips and developing solution (equal parts white vinegar and rubbing alcohol) to determine whether or not the foods and liquids contain protein. I begin the lab portion of the lesson by discussing how to handle test strips and read the results. If the students handle the test srips directly, this can affect the test results. I ask students to use tweezers to place the test strips into the test tray and to transfer the test strips to the test solution. I also set up a protein test station with a tray of solution prepared for each food and liquid the students will test.
I distribute a copy of the protein lab worksheet to each student. I ask students to predict which foods and liquids have protein and to record their predictions on their lab sheet. I then review procedures for the lab. I inform students that they must place a test strip in each section of the test trays after adding the food and liquid samples. I give students 10 -15 minutes to accomplish this part of the lab. I then announce each food and liquid sample and have all students bring their test strips to the developer solution at the same time. This is useful because the test strips must be immersed in the developer solution for 5 minutes and then be read promptly. Having all students add their test strips to the solution at the same time makes it easier to read the results. After the test strips have been immersed for 5 minutes, I call students to read and record the results.
After all students have viewed the test strips, I ask students to share their results with one another. As students share, I record the results on the class chart. Since all test strips are developed in the same solution, there is little variation in results.
I close the lesson by asking students to complete the "L" section of KWL chart. To do so, students write anything that they have learned. These statements can range from the obvious ("Milk has protein") to more complex generalizations based on the results ("No junk foods we tested have proteins"). I also encourage students to revisit both of the two previously completed sections of the KWL chart. In the "K" section, I ask students to idenitfy any misconceptions that they recorded in the section. I also ask students to look in the "W" section and put a star by any questions that were answered in the day's lab. By revisiting the KWL chart, students can address misconceptions, refine their thinking, and select questions that need further research or exploration. A photo of a student's completed KWL can be found HERE.