A slice of a circle is a fraction of the whole one, and once that fraction is named the rest is arithmetic already known. These free printable worksheets ask for the curved edge or the area of a sector, with the angle drawn on the figure.
If they get stuck
The answer key prints on a separate page.
A 90° slice is a quarter of the circle, so its curved edge is a quarter of the circumference and its area is a quarter of the area. Writing the fraction down first — 90 over 360, which is one quarter — turns both questions into one multiplication and removes any need to remember two separate formulas.
The two questions are mixed on purpose. Arc length uses 2πr and sector area uses πr², and a page of only one kind lets a child pick the formula by habit rather than by reading. Which is being asked for is stated beside each figure, and the units are the giveaway: a length is in cm, an area in cm².
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Arc length and sector area, step by step