Assessment
The final accumulation of all the materials that go along with this activity will be the student’s assessment. The students should have research on typhoid fever, Mary Mallon, and the lab activity.
The teacher can decide how much he/she thinks each worksheet, lab, and the journal should be worth and grade accordingly.
Content Provider
PBS - NOVA
Day by Day Summary of Lesson
Day 1: Have a day planned in the library so that the students can research typhoid fever, Mary Mallon, and school health policies. This will give the students information to discuss in the classes to follow.
Day 2: Today the students will partake in the laboratory exercise that will show the students how easy the transmission of diseases really is. This lab will take 4 days to complete; during this time the students will take down notes and observations each day of this lab. Students should use their lab notebook to write down observations. If they do not have a lab notebook, they need to keep their written records in a safe spot.
Day 3-6: Students will start class each day by writing down observations that they see about their beets.
Day 6: After the students have completed the research and the laboratory exercise, the students should break up into their laboratory groups. Using the information that they have gathered, the students should answer the questions on the worksheet that deal with all of the information they have compiled.
Duration
4-6 days
Essential Question
Is it possible for a healthy person to spread germs and diseases that may get others sick?
Objectives for Laboratory
- Students will be looking for bacterial growth on beets to see how not washing your hands can spread germs.
- Students will understand how bacteria can be transferred through food by handling it. And they will see if the students who did not handle it still could give the beets the bacteria.
Description
This activity brings together history and science by focusing on the discovery of typhoid fever in a healthy carrier. The purpose of this lesson is two-fold. Firstly, students will research Mary Mallon, who was said to be the first healthy carrier of typhoid fever. Secondly, students will do a laboratory experiment to see how quickly bacteria can travel.
The students will use the internet to research typhoid fever, what causes it, how it is spread, symptoms, and treatment. They will also research Mary Mallon to find some information about her and why she is said to have transferred the disease to so many people.
Website(s)
NOVA- The Most Dangerous Woman in America
Laboratory Procedure
Teacher Materials
2, 14.5 oz. cans of sliced beets (10-12) slices per can
Can opener
1 pair new plastic gloves
Plastic tongs
Isopropyl alcohol (for disinfecting)
Materials For Each Lab Group
Copy of the “Which Wash Wins?” student handout
Copy of the “Hand-washing Methods” student handout
3, 100 mm x 15 mm sterile plastic Petri dishes
Cotton swabs
Tape
Permanent marker
Access to sink with water
Regular soap
Antibacterial soap (with antiseptic like triclosan)
Hand sanitizer (with ethyl or isopropyl alcohol)
Paper towels
Teacher Procedure
1.) Prior to this activity, thoroughly disinfect the tongs by spraying or soaking them in alcohol. (You may want to wash the can opener and tongs in a dishwasher and store them in a plastic bag prior to disinfecting.)
2.) Ask students if they have ever seen a sign in a restaurant bathroom that reads: “Employees must wash hands.” Why do students think these signs are there?
3.) Ask students what they think is the best way to keep hands clean. What kinds of products, if any, do they think would be best? What is the optimal water temperature when washing hands? What amount of time spent washing? Write student answers on the board.
4.) Tell students they are going to test four methods (a fifth group will serve as the control) of hand hygiene. (You may want to adapt these methods to reflect students' suggestions.) The methods are:
water only regular soap antibacterial soaphand sanitizer
5.) Organize students into five teams of 4 students each (modify to fit your class size) and provide each team with a set of materials. Each team will be assigned one of the following variables:
Control Team: No washing method
Experimental Team 1: washing with water only
Experimental Team 2: washing with regular soap and water
Experimental Team 3: washing with antibacterial soap and water
Experimental Team 4: washing with hand sanitizer only
6.) Have each team develop a hypothesis of which of the four methods it thinks will work best and why. Then have students conduct the experiment as outlined in their handouts. As students start their hand-washing techniques, put on the plastic gloves and open the two can of beets. Have each team use the tongs to retrieve three beet slices, one for each of the team’s three Petri dishes. You may want to disinfect the tongs with alcohol between each use.
7.) Have the students record the results in a journal each day, making sure to include diagrams. After four days, compare the growth on the beats from the different teams. As a class, answer the following questions:
-How did each set of beets compare to the control set of beets?
-Which experimental team’s beets had the least bacteria?
-What areas (palms, in between fingers, under nails) were washed the most thoroughly by each technique? Which areas were washed least thoroughly?
-Was there any growth on the control beets?
8.) Discuss the results with students. What results were most surprising? It’s likely that all the beets showed some microbial growth because the experiment was not completely sterile. Discuss with the students where microorganisms might have come from (beet, plastic tongs, cotton swab, Petri dish, tap water, air). How could the experiment have been made more sterile?
9.) To conclude, discuss with the students why and when it is appropriate to wash hands.
There are post-lesson questions that the students can answer on the last day of the lab. These questions can help spark a classroom discussion.
"Which Wash Wins?" Student Handout"Hand-Washing Methods" Student HandoutPost-Lesson Questions
Research Questions for Pre-Lab Activity
These worksheets can be used for the students to find information on Typhoid fever and Typhoid Mary. These are to be used for the day in the library.
Typhoid Fever Student WorksheetTyphoid Fever Teacher AnswersTyphoid Mary Teacher AnswersTyphoid Mary Student Worksheet
