We ask for requirements first (expected answer = whatever you think is OK)
We start with positive testing, not with breaking the toaster (negative testing)

Functionality Testing
Start with requirements:
- works out of 110Volt power line (indicated by green LED light)- 4 levels of heat are available
- Level 1-5 minutes toasted
- Level 2-4 minutes toasted
- Level 3-3 minutes toasted
- Level 4-1 minutes toasted
- 2 slots are available
- Left slot could be used as a standalone slot
- Right slot could be used as a standalone slot

Then we do test cases (preferably one test case for one requirement)
1. 110V supply Plug into 110V plug green LED light is ON
2. 4 levels of heat Turn and count 4 positions are there
3. Level 1 heat Set level 1 and toast takes 5 minutes
4. Level 2 heat Set Level 2 and toast takes 4 minutes
7. 2 slots toasting Toast 2 slices at a time toasted normally
8. Left slot toasting Toast one slice in a left slot toasted normally
9. Right slot toasting Toast one slice in a right slot toasted normally

Then we move to non-functional requirements:
- Environmental (moisture, temperature, evaporation of chemicals, decoloration, etc.)
- Transportation (vibration, cargo, packaging)
- Safety
- Supporting documentation