Students create large-scale models of microfluidic devices using a process similar to that of the PDMS and plasma bonding that is used in the creation of lab-on-a-chip devices. They use disposable foam plates, plastic bendable straws and gelatin dessert mix. After the molds have hardened overnight, they use plastic syringes to inject their model devices with colored fluid to test various flow rates. From what they learn, students are able to answer the challenge question presented in lesson 1 of this unit by writing individual explanation statements.

Students obtain a basic understanding of microfluidic devices, how they are developed and their uses in the medical field. After conducting the associated activity, they watch a video clip and learn about flow rate and how this relates to the speed at which medicine takes effect in the body. What they learn contributes to their ongoing objective to answer the challenge question presented in lesson 1 of this unit. They conclude by solving flow rate problems provided on a worksheet.

Students perform an activity similar to the childhood “telephone” game in which each communication step represents a biological process related to the passage of DNA from one cell to another. This game tangibly illustrates how DNA mutations can happen over several cell generations and the effects the mutations can have on the proteins that cells need to produce. Next, students use the results from the “telephone” game (normal, substitution, deletion or insertion) to test how the mutation affects the survivability of an organism in the wild. Through simple enactments, students act as “predators” and “eat” (remove) the organism from the environment, demonstrating natural selection based on mutation.

Building on their understanding of graphs, students are introduced to random processes on networks. They walk through an illustrative example to see how a random process can be used to represent the spread of an infectious disease, such as the flu, on a social network of students. This demonstrates how scientists and engineers use mathematics to model and simulate random processes on complex networks. Topics covered include random processes and modeling disease spread, specifically the SIR (susceptible, infectious, resistant) model.

Students explore the applications of quantum dots by researching a journal article and answering framing questions used in a classwide discussion. This "Harkness-method" discussion helps students become critical readers of scientific literature.

Students learn that engineers develop different polymers to serve various functions and are introduced to selectively permeable membranes. In a warm-up activity, they construct models of selectively permeable membranes using common household materials, and are reminded about simple diffusion and passive transport. In the main activity, student pairs test and compare the selective permeability of everyday polymer materials engineered for food storage (including plastic grocery bags, zipper sandwich bags, and plastic wrap) with various in-solution molecules (iodine, corn starch, food coloring, marker dye), assess how the polymer’s permeability relates to its function/purpose, and compare that to the permeability of dialysis tubing (which simulates a cell membrane).

Students learn how viruses invade host cells and hijack the hosts' cell-reproduction mechanisms in order to make new viruses, which can in turn attack additional host cells. Students also learn how the immune system responds to a viral invasion, eventually defeating the viruses -- if all goes well. Finally, they consider the special case of HIV, in which the virus' host cell is a key component of the immune system itself, severely crippling it and ultimately leading to AIDS. The associated activity, Tracking a Virus, sets the stage for this lesson with a dramatic simulation that allows students to see for themselves how quickly a virus can spread through a population, and then challenges students to determine who the initial bearers of the virus were.