Virtual Labs Lesson Plan: Controlling Water Activity in Food

Lesson Procedure:

1. Review the Understanding Water virtual lab that students explore prior to this lesson.
2. Ask students why the concept of water activity is important to food preservation.
3. Tell students that they will have the opportunity to complete another virtual labs; this time, on controlling water activity in food. They will test water activity levels of dried corn and explore how they change under three different storage environments.
4. You may want to display the first few screens of the game for students to see, and discuss the background information that is shared. Draw students' attention to the statement that when water activity is less than 0.6, almost all microbes stop growing, and be sure students understand that Vegetables are usually dried even further to water activity of 0.3 or 0.2 for quality and storage.
5. Provide 10-15 minutes for students to complete the interactive on their own computers. Alternatively, you can have students work with a partner to complete the lab.
6. You may want to have students conduct further research into the traditional methods of preserving corn by drying or other food preservation. How might ancient peoples have dried corn? What would be the importance of drying and preserving food in ancient cultures?
7. Use the game quiz to assess student learning.
8. If you have access to a water activity measuring tool, you may want to have students run their own "controlling water activity" experiments in the classroom. A workaround would be to design a similar experiment that does not require measuring water activity, but is indirectly related to that measurement, such as mass. For example, you may want to have students explore how the mass of dried corn increases when stored in a damp environment due to absorbing the water molecules around it, indicating increased water activity.)