Lesson Links to Try

Click to see how these work:

Similar polygons/proportions (Sect 1/2)
http://www.educreations.com/lesson/view/similarity/373421/

Previous links for Sect 3/4/5 if you haven't tried them:

Subtracting mixed numbers

http://www.educreations.com/lesson/view/subtraction/357154/

+/- with variables:
http://www.educreations.com/lesson/view/variable-add/357258/