TRANSCRIPT

VideoGirl1: Hi. I'm Kia.

VideoBoy1: And I'm Justin.

VideoGirl1: You must be the tree house detectives.

Boy1: Yes. We are. And I'm trying to avoid infectious bacteria.

Boy2: We need to learn more about how infectious diseases spread.

VBoy1: We can help. Our mentor for the Society of Women Engineers helped us with a great experiment that simulates an epidemic.

Boy2: An epidemic occurs when the majority of people in a group all get an infectious disease. How do you simulate an epidemic?

VGirl1: First our teacher, Ms. Fragga, prepared the test tubes for each student. All the test tubes had water in them except for one, which had a solution of ammonia. But we didn't know which one was which.

Boy1: Why only one?

VGirl1: To simulate the student who has the cold virus.

Boy2: What did you do next?

VBoy1: We each use an eyedropper to exchange four drops of fluid with four other people to simulate an exchange of body fluids such as eating or drinking with another person. We also made sure to record the name of the person we exchanged the fluid with.

Boy1: Why was that important?

VBoy1: We wanted to see if we could trace the virus back to the original person.

Boy1: How could you tell who was infected?

VGirl1: After we finished exchanging the fluids, Ms. Fragga added a hundred drops of an indicator made from cabbage leaves to our test tubes. If the test tube was infected, it changed color to yellow, green, blue, or purple.

Boy2: Why the different colors?

VBoy1: The color differences were due to the amount of ammonia in each test tube. The infected test tube turned yellow and the ones with the next greatest amount of ammonia turned green. The ones that were only slightly infected with ammonia turned blue and the ones that weren't infected at all turned purple.

Boy2: I understand. The test tubes with the most ammonia had the most exposure to the cold virus.

VBoy1: That's correct. That particular student had an exchange or been exposed to the virus more than other students.

Boy1: How many students were infected at the end of the experiment?

VGirl1: Twelve out of fifteen students were infected. That's eighty percent that contracted the cold virus.

Boy2: It's good to know that not all of the students were infected.

VBoy1: Yes it is. And it's even better to know that you can prevent the spread of disease by not exchanging body fluids with other people. To be safe, it's best not to eat or drink after anyone and to try and avoid contact with sick people.

Boy1: That's good advice. Thanks for all your help.

VGirl1: You're welcome. Anytime. Good luck Jacob. Hope you stay well.

VBoy1: And thanks to SWE for all their help.

VGirl1: Goodbye from our elementary school in Key West, Florida.