Khan Academy is a great place to go for teaching videos. When I want to watch a video on a specific math topic, I simply do a Google search. So for instance, if I were having trouble with long division, I'd do a Google search for Khan Academy long division videos.
The following is a link to a fabulous power point on AREA and PERIMETER: http://www.whs.rcs.k12.tn.us/teachers/bartc/AreaorPerimeterirregular%20shapes.pdf
The following is a link on how to place rational numbers on a number line: https://learnzillion.com/lesson_plans/5095locaterationalnumbersusinganumberline

The following is a link to a video on converting among decimals, fractions, and percents: http://www.teachertube.com/video/mathvideotutorialbymrleefractionsdecimalspercents19369?utm_source=videogoogle&utm_medium=videoview&utm_term=video&utm_content=videopage&utm_campaign=videoviewpage





The video below shows you how to line up decimals for adding and subtracting them (and comparing them).
The following is a link to a Khan Academy video on Greatest Common Factor: https://www.khanacademy.org/math/insixthgrademath/playingnumbers/highestcommonfactor/v/greatestcommondivisor



