Prompt Testing: evaluate and improve your prompts

Copy this, open Claude, paste it, and Claude will walk you through the lesson step by step.

For a grown-up: Claude is for adults (18+). Copy this, paste it into Claude, and use the answer to explain the lesson to your child.

I'm learning "Prompt Testing: evaluate and improve your prompts" on The Future Market. Lesson 1: "Why test a prompt".

What the lesson teaches:
- A prompt can look perfect on the one example you tried and fail on the next. Testing means running the prompt on many realistic inputs and scoring the results.
- Anthropic's documentation on defining success criteria and building evaluations says that defining success criteria and then designing evaluations to measure performance against them is central to prompt engineering. Its flowchart of the process runs: test cases, preliminary prompt, iterative testing and refinement, final validation, ship.
- An eval (short for evaluation) is a test you run on a prompt: a set of inputs plus a way to score the answers.
- Anthropic's prompting guide says that where a technique names a specific model, it was measured on that model, and you should re-check it against your own evals before applying it to another model. So tests also protect you when the model changes.
- AI answers are not identical each time. Running the same prompt twice can give different results, so one good run is weak evidence.
- Testing is not only for programmers. A teacher, an office worker or a shop owner can run a test set by hand in a spreadsheet.
- Without testing - With testing

The exercise I'm working on:
Run one prompt of yours on three different inputs, twice each. Write down every difference you notice between runs.

I'm stuck. Please:
1. Explain the main idea in plain, simple words with one everyday example.
2. Walk me through the exercise one small step at a time. Ask me what I've done so far before giving the next step.
3. Don't just give me the final answer. Help me do it myself, and check my work when I share it.

I'm a parent helping my child (about 8 years old) with a lesson called "Why test a prompt" from the course "Prompt Testing: evaluate and improve your prompts".

Here's what the lesson says:
If a cook makes one good soup, we do not yet know if the recipe is good. Maybe the cook was lucky that day. A recipe is good when it works on many days, with many pots. We test a prompt the same way: on many inputs, not just one.

The activity:
Run one prompt of yours on three different inputs, twice each. Write down every difference you notice between runs.

Please explain this so an 8-year-old understands: short sentences, a fun everyday example, and no hard words.
Then give me 3 simple questions I can ask my child to check they understood, and a way to do the activity together, one tiny step at a time.