A test list narrows things down
Testing removes the ones that cannot do the job. What is left is a short list, not an answer.
Step 1: Something to Notice
Watch first. The explanation comes later.
Set the purpose to a hammer handle. The table says wood is a good choice, metal is a good choice, and so is glass.
Would you like a glass hammer? What did the table not know?
Step 2: Find Out
Ask the table for a hammer handle and look at what it says.
Step 1 — Predict
A hammer handle has to be hard. How many of the five materials are hard?
Choose what you think will happen. You cannot see the experiment until you do — guessing first is what makes it worth watching.
Step 3: So Here Is Why
Now the explanation, after you have seen it happen.
It only knows what you asked
A test list only knows the questions you put in it.
So add the test
A silly answer tells you which question you forgot. Add does it shatter, and glass drops out.
Then try it
In the end you have to build it and use it. Real use asks questions nobody wrote down.
Step 4: A Common Mistake
Lots of people think
“If the table says a material suits the job, it is a good answer.”
Step 5: Adding the Missing Question
The same idea somewhere new.
The fix is to test the thing you forgot. Add a "does it shatter?" test and glass drops out immediately. Every good test list started as a shorter one that let something silly through.
Step 6: Think It Through
Practice makes it stick.
The Hammer
Problem 1 of 1
Wood, metal and glass are all hard. Which would you actually use for a hammer handle?
Good Enough, or Best?
1 of 3
The table says a material suits the job. Does that make it the best choice?
2 of 3
Glass passed the hammer handle test. What test was missing?
3 of 3
Put the steps in order.
- 1Test the materials
- 2Look at what passed
- 3Build it and try it
- 4Work out what the job needs
Step 7: Quick Check
Show what you know.
Question 1 of 1
A table of tests says three materials suit a job. What do you do next?
What You Found Out
- Tests narrow the choices down. They do not decide.
- A table only knows what you asked it.
- When something silly passes, add the test that was missing.
For the grown-up
Change one thing only — To find out which cloth soaks up most water, use the same amount of water, the same size piece, and the same time for each. If you change two things at once you cannot tell which one mattered.
The results still need judging — A table of results narrows it down and does not decide for you. The most absorbent cloth might be too expensive or too thick. You still have to weigh things up.
A test list narrows things down — Running every material through the same tests gets rid of the ones that cannot do the job. What is left is a short list of possibles. That is genuinely useful — but a short list is not an answer, and you still have to choose from it.
It only knows what you asked — A test list is not clever. It only knows the questions you put in it. Glass passes "waterproof" and "see-through" and so it comes out top for a lunch box — because nobody thought to ask whether it shatters when dropped.
So add the test — When a silly answer comes out, that is useful information: it tells you which question you forgot. Add "does it shatter?" and glass drops out at once. Every good test list started as a shorter one that let something silly through.
Then try it — In the end you have to build the thing and use it. Real use asks questions nobody wrote down — is it too heavy, does it get slippery, does it last a week? Building it is the only test that asks all of them at once.