I begin the lesson by bringing in a bag of french fries. I ask students what they notice about the bag of fries. Students frequently remark on the smell of the fries, the appearance of the fries, and how the french fries have discolored the bottom of the bag. I tell the students that the discoloration at the bottom of the bag tells us that the food contains fat. In the day's lab, the students will use paper bags to determine whether a food or liquid contains fat. This demonstration helps students to connect the idea of fat-containing foods to their own everyday experiences.
I then distribute a copy of the fats lab record sheet to each student. In the day's lab, students will be testing food and liquid samples for the presence of fat. To accomplish this, students will use paper bags as a test material for fat. In order to determine whether a food or liquid has fat, the student must rub food samples against the paper bag and drop liquid onto the paper bag. I demonstrate how to do this using the document camera. I rub a food sample and and drop a liquid sample on the paper bag and allow students to make observations. We discuss how a stain on the bag indicates the presence of fat, like the stain on the french fry bag tells us that the fries contain fat.
I then provide students with an opportunity to test each food and liquid sample. A video of my students conducting the lab can be found here. A sample of a student's completed lab worksheet can be found here. A photo of the student's test strips can be found here.
After the completion of the lab, I ask students to share their test results with their peers. In this lab, I ask students to share their results using the document camera. I use popsicle sticks labeled with each student's name to randomly choose a student to share. I ask the chosen student to bring their paper bag square up to the document camera to show their findings. After each child presents, I provide time for any other student in the class to share contrary findings. Once we have reached consensus, I record the class' test results on our class food and liquid charts.
One key understanding that I want my students to obtain is that there are different kind of fats and that each type of fat has a different effect on the human body. To help students learn more about fats, I give a homework reading assignment to each student. The article I assign to students comes from the STC curriculum, however, many articles about fats will work to provide students with this information. After students have completed their independent reading, I ask them to complete the fat questions assignment. A sample of a student's completed questions can be found here. This serves as a quick formative assessment of student understanding about fats.