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Class 5 science · A.5 · Matter

Conservation of mass

Mass stays the same when matter changes form or reacts—unless something leaves the system like gas or water vapor.

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  1. In science class, Leo asks: When you mix salt and sugar in a bowl on a scale, does the total mass change?

    • Yes
    • It gets smaller
    • No (right)
  2. In science class, Kai asks: A student evaporates water from a beaker. Does the total mass change?

    • Yes, because water turns to vapor and leaves
    • No (right)
    • Yes, the container gets lighter
  3. Hana and Ana are curious. If you burn a piece of paper, does the total mass change?

    • Yes, ash is heavier than paper
    • Yes, it gets lighter
    • No (right)

Tip: Mass stays the same when matter changes form or reacts—unless something leaves the system like gas or water vapor.

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