Conflating physical quantities with numbers
Wrong Track: The energy is 3.
Wrong Track: it's 30 in the shade.
Wrong Track: the kettle is nearl 3 and that's big.
Right Lines: The kettle has a power of 3.2 kilowatt
A physical quantity is always number and unit
Just as numbers need anchoring amongst other numbers to aid comprehension, so Physical quantities such as power, temperature, brightness, power and time need both number and a unit. Providing both gives clarity and precision: it's clear what's being said. It may not be accurate, but you could find out that it's wrong.
Always use the same unit when comparing quantities — for example compare powers using either watts or kilowatts
Prefer to write out units longhand, rather than using abbreviations. Less cryptic is probably more approachable for younger children.
