Learning and Teaching for Mathematical Literacy

These videos demonstrate that a burning carbon-based fuel (candle wax) emits carbon dioxide. The gases are captured and then tested with lime water - which turns milky in the presence of CO₂.

Note that you should never accept a single, unverified YouTube video as proof - but this is a classic experiment and many other videos showing the same result can be found online. Better still, this simple experiment is easily replicated in a school chemistry lab.