Circle partsRadius to 12
Use π = 3.14. Find the area of each slice.
A sector is a slice of a circle, and its area is that same fraction of the whole circle's area. These free printable worksheets keep to the slice alone.
If they get stuck

The answer key prints on a separate page.
The circle's area is πr², and the slice is that times the angle over 360. Writing the fraction of the turn down first is the habit worth building: 120 over 360 is a third, and a third of the circle is easier to picture — and easier to check — than a formula with two multiplications in it.
Every angle here divides 360 exactly and every answer lands on two decimal places, so nothing on the paper says round to the nearest tenth. π is 3.14 throughout, the same as every other circle sheet on the site.
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Sector area, step by step