Slide outline for Lesson 6.7. Nineteen slides across two days: Day 1 slides 1 to 10, Day 2 slides 11 to 19. Slide 6 is the treatment table and it stays on the board all of Day 2. [Sal: photograph the four muffins in a row at the end of Day 2. That photo is the review slide for items 9 and 10 on the Cooking Methods Check.]
DAY 1
Quick Bread Science Lab
- Unit 6, Lesson 6.7, Day 1
- Topic 6.2 Food Preparation Methods and Science
- Four batches, one difference
- This is an experiment, not a recipe
Teacher notes
Image: four muffins in a row, visibly different heights, cut in half.
Do now
- A muffin and a loaf of bakery bread both rise
- Do they rise the same way?
- Write yes or no and one guess about what makes each one rise
Teacher notes
Take four answers, correct none. A student who says "yeast" for the bread has half the concept already; give them the Batch E stretch.
Watch this
Teacher notes
Image: a clear cup with baking soda, and a hand pouring vinegar into it, foam climbing over the rim onto a tray.
This is the hook. Do it live, with no warning. Then: "That gas is what lifts a muffin. Today you figure out exactly which ingredient makes it."
How leavening works
- Baking powder and baking soda both make carbon dioxide gas in a wet batter
- The gas makes bubbles
- The bubbles get trapped and push the batter up
- The heat sets the batter around them, so it stays up after it cools
Teacher notes
Image: a cross-section drawing of batter with bubbles rising through it.
The difference between the two
- Baking powder already has its own acid mixed in. Water and heat are enough
- Baking soda has no acid of its own. It needs an acid in the recipe
- Acids in a real kitchen: buttermilk, yogurt, vinegar, lemon juice, brown sugar, cocoa
- No acid means the soda mostly sits there and leaves a soapy taste
Teacher notes
Students mark which one needs the acid.
The four batches
| Batch | Treatment |
|---|---|
| A (control) | 1 tsp baking powder |
| B | none at all |
| C | 2 tsp baking powder |
| D | 1 tsp baking soda, no acid |
Teacher notes
This slide stays on the board for all of Day 2. Everything else in all four batches is identical.
The four-cup fizz test
- Cup 1: baking soda plus water
- Cup 2: baking soda plus vinegar
- Cup 3: baking powder plus water
- Cup 4: baking powder plus vinegar
Teacher notes
Run all four in order and call the result out loud each time. Then ask the class to state the rule from the evidence, not from the slide.
Variable and constants
- Independent variable: the one thing we change on purpose. The leavening
- Dependent variable: what we measure. Height, crumb, taste
- Constants: flour, sugar, salt, milk, oil, egg, batter per liner, oven temperature, bake time, same oven, same shelf
- The control batch is the ruler. Without it, the other three mean nothing
Teacher notes
[Sal: ask the science teacher which words they use for independent and dependent variable and use theirs instead of these. It is free and it makes both classes stronger.]
Predict
- One prediction per batch
- Rank the four by expected height
- Plus one sentence: what will Batch D taste like, and why?
Teacher notes
Predictions are written before any batch exists, so they cannot be adjusted after. Collect nothing; the sheet comes back tomorrow.
Tomorrow
- Roles on your card
- Four bowls, labeled A, B, C, D
- I dispense the leavening, not you
- Exit card: the one thing we are changing is ___. Batch ___ will rise the highest because ___
- * *
DAY 2
Teacher notes
Say the leavening rule out loud today so it is not a surprise tomorrow. One student adding baking powder to Batch B ends the experiment.
Bake, Measure, Conclude
- Unit 6, Lesson 6.7, Day 2
- Four bowls, one difference, no cheating
- Whatever comes out of that oven is the answer
Teacher notes
Image: four labeled mixing bowls in a row on a station counter.
Do now
- Read your prediction for Batch B
- Do you still believe it? Yes or no, one sentence
Teacher notes
Thirty seconds. Then: "Whatever comes out of that oven is the answer, and it is not up for a vote."
The six-step routine
- Hair back
- Sleeves up
- Wash hands
- Sanitize surfaces
- Clean as you go
- Station check before dismissal
Teacher notes
Same six steps, same order, every lab all year. Start the timer when every station is standing with hands empty.
Mix, in this order
- Dry ingredients measured and leveled into the labeled bowl
- I come around with the leavening
- Wet added: milk, oil, egg
- Stir about fifteen strokes and stop. Lumps are fine
- 1/4 cup of batter into each labeled liner
Teacher notes
Overmixing makes tough batter and it confounds the test. Say "fifteen strokes, lumps are fine" at every station, once.
The flowchart
Minute: 0 5 10 13 20 25 28 35 40
Mix: |======four batches=======|
Bake: |===13 min===|
Measure: |before| |after, crumb, taste|
Clean: |as you go |ZONES|Teacher notes
Measure the before height while the batches wait. I load and unload the oven; nobody else touches it.
What to measure
- Height, with the ruler, before and after
- Crumb: split one open. None, few, or many holes
- Taste, if you choose to. Own fork, own plate
Teacher notes
Image: a ruler held against a split muffin, with the rise marked.
A warning about Batch D
- It will taste soapy or metallic to most people
- Nothing is wrong with you
- That taste is the evidence
Teacher notes
Say this before anyone tastes. Students who are not warned decide something is wrong with them or with the food.
Conclusion frame
- The data showed ___
- My hypothesis was supported / not supported / partly supported, because ___
- My evidence is ___
- One thing that could have gone wrong is ___
Teacher notes
Take two conclusions out loud. Batch C often rises highest and then collapses; that is the best data in the room and not a mistake.
Station check
- Oven off, tin on the trivet
- Four bowls washed, dried, put away per the map
- Counters wiped and sanitized, sink empty
- Floor swept, trash out
- Leavening jars back on my table
Teacher notes
When I sign a station, the Station Manager reads the station's one-sentence conclusion out loud. Lab sheets collected at the door. Keep one muffin from each batch under wrap for the review.