A measuring instrument similar to compasses with curved legs for measuring thickness (diameter) of curved (convex) objects or, turned outwards, for measuring cavities. Example
A calendar represents the way in which a year is broken up into months, weeks and days. Example
Measurement from side to side, also called width.
A straight line which divides an angle, or an interval, into two equal parts.
Calculating aid. Calculators are electronic. They are battery or solar powered. Example
To cut or divide into two equal parts. Example This angle has been bisected.
A prefix which stands in front of words and means two or twice. Example