Which shapes are considered quadrilaterals? View and learn that two dimensional shapes with four straight sides are considered quadrilateral. The rhombus, parallelogram, rectangle, and trapezium are only few of the fabulous shapes...

Another good presentation by Christine Berg is here for you. In it, learners are coached on definitions of area and perimeter and are shown how to perform calculations for both. They also see how to calculate the area of a triangle by...