Halves, quarters, time and symmetry

Fractions of a whole

$\tfrac12$, $\tfrac14$ and $\tfrac34$ all describe equal parts of one whole. Two pieces of different size are not halves, no matter how the cut was made.

Time

On a clock face the long hand points at a number $n$, and that means $n\times5$ minutes — not $n$ minutes. Adding minutes only changes the hour when the total passes $60$.

Symmetry

A line of symmetry is a fold line: fold along it and the two halves must land exactly on top of each other.