Grades 6, 7 and 8 - Math - Middle School - Perimeter and Area — Flashcards

Area is the size of the surface of a two-dimensional (2D) or three-dimensional (3D) shape. The area of a three-dimensional shape is worked out by adding the area of each of its faces together. The area of each of its faces is worked out in the same way as the area of 2D shapes.
The perimeter of a shape is the distance around its edge. To work out the perimeter of a hexagon multiply the length of one of its sides by 6.
When working out the perimeter of a shape with straight edges, it is a good idea to mark in the length of each edge.  Sometimes, particularly with complex shapes, not all the lengths are given and you have to work them out.  Once you have them all in place, start at one corner and imagine walking all the way round the shape and back to the start.  Total up the distance you have traveled, and that is your perimeter!  Don’t forget to include units – as it is a length, this will usually be meters or cm.
If you are asked for the perimeter of a shape that includes part of a circle, for example a quarter circle, don’t forget to add in the straight edge
To work out the area of a rectangle multiply the length of its longest side by the length of its shortest side.  This will give you an answer in square mm, cm or m (mm² cm² or m²).