Open Bench · Unit 1 of 8
What a disease actually isWhy does one kid get eczema and the kid next to them doesn't?
The difference between a symptom and a mechanism, taught through an allergic reaction. Students leave with a hand-drawn map of what happens in the body, which they will keep correcting for the next seven weeks.
Length
60 minutes
Tracks
Explorer (Grades 6–8) · Builder (Grades 9–12)
Cost
Free, permanently
Licence
CC BY 4.0
Objectives
By the end of the hour, a student can do each of these without being prompted.
- 01
Tell the difference between a symptom, a cause, and a risk factor, and give an example of each.
- 02
Describe in plain words what the immune system is for and how it mistakes a peanut for a threat.
- 03
Draw the chain of events in an allergic reaction and point at the step a medicine could interrupt.
- 04
Say out loud one thing about this disease that nobody currently knows.
Run of show
The hour, minute by minute.
Timings are a plan, not a rule. The segment most worth protecting when you run late is noted in the teacher notes below.
- 10 min
The itch question
Open with a real case: two children in the same house, one with severe eczema. Ask the room why. Collect every answer on the board without judging any of them. Most will be risk factors mistaken for causes, which is the whole lesson.
- 15 min
Symptom, cause, risk factor
Sort the board's answers into three columns. Students argue about the placements. The argument matters more than the sorting.
- 15 min
The immune system in fifteen minutes
Barrier, sentinel cells, the alarm signal, the overreaction. Keep it to four moving parts. Every additional part costs you a student.
- 15 min
Draw the chain
Each student draws the sequence from exposure to symptom, then marks with an X every point where you could imagine interrupting it.
- 5 min
What nobody knows
Everyone names one open question. Collect these. You will return to them in Unit 8 and several will still be open, which is the most honest thing you can show a student.
The activity
The mechanism map
- 1
Pick one allergic condition: eczema, peanut allergy, or hay fever.
- 2
Draw the path from first exposure to visible symptom, left to right, with at least five steps.
- 3
Mark every step where you could imagine a medicine interrupting the chain.
- 4
Circle the step you would attack first, and write one sentence on why.
What you hand in
One page, drawn by hand or on screen, that you will revise at the end of Unit 3 and again at the end of the course.
Tools, all free
- Paper and pencil
Unit 1 is deliberately analog. Screens come later.
Free, no account, for students who would rather draw on a laptop.
Explorer track swap
Explorers draw the map as a comic strip with a character instead of a flow diagram. The science is identical and the retention is better.
The misconception to expect
“An allergy means the immune system is weak.”
An allergy is the immune system working hard against the wrong target. Strength was never the problem. Aim was.
Teaching it
Notes from the room.
How you know it landed
A student has it when they can point at their own drawing and say which step is a symptom and which is a cause, without being prompted.
- 01
Do not correct wrong answers in the first ten minutes. The sorting exercise corrects them, and self-correction sticks.
- 02
Somebody will ask whether allergies are caused by being too clean. Say that it is a real hypothesis, that it is contested, and that Unit 3's reading covers it. Do not resolve it for them.
- 03
If a student in the room has a serious food allergy, ask them privately before class whether they want to be the expert that day. Many do. Some very much do not.
Reading for this unit
The papers behind the hour.
Optional for Explorers, expected for Builders. Full notes on each one are in the reading room.
- R-06
Does the epithelial barrier hypothesis explain the increase in allergy, autoimmunity and other chronic conditions?
Nature Reviews Immunology · 2021
An argument that detergents, surfactants, microplastics, pollutants and processed food damage the skin, gut and airway linings, and that this damage drives the global rise in allergic and autoimmune disease.