The way I teach this skill is very easy to learn and your child will be prepared for success in Geometry.
I will show students how to do an exercise on the white board. They will learn  by actually doing example exercises during class. I will repeat with another exercise and will explain as many times as needed until the students are ready to do the exercises by themselves. Once started, I will check their answers for accuracy and follow up with any necessary explanations. I encourage all participants to try as many exercises as possible. I follow up the class with an upload of homework with the solutions.

The course breakdown is as follows:

Week 1: Learning to calculate the angles of a quadrilateral. Numeric and algebraic.

Week 2:Calculating perimeter. (Squares, rectangles ,parallelograms, trapezoids and 
                                                         triangles.)

Week 3: Calculating area. (Squares, rectangles, parallelograms, trapezoids and triangles.)

Week 4:  Calculating area of composite figures.(L and U shaped rectangles.)

Week 5: Introduction to surface area. (Cubes, rectangular prisms and rectangular pyramids.)

Week 6: Calculating volume.(cubes, rectangular prisms and cylinders.) 

Week 7: Circles. (Circumference, area and introduction to Pi.)
                              (Arc length and Area of a Sector)

Week 8: Spheres.(3-D circles, surface area and volume.)

Week 9: Calculating areas within areas.(concentric circles etc.)

Week 10: Review with Applications.