I'm sure the name Pixar rings a bell. You may not know exactly who they are but you've seen lots of their work especially if you have kids you take to the movies a lot.
These are the folks who made Brave, Monsters University, Up, Wall*E and tons of other animated films. They have gotten together with Khan Academy to offer Pixar in a Box. No, its not the company packaged in a gift wrapped box under the Christmas tree. Its a free online course that was created by Pixar for Khan Academy.
Currently, the course is a work in progress but they have 6 topics up and ready to go. Each topic has two lessons, the first is the general introduction to the topic while the second lesson is math specific and geared for grades 7 to 12. Over time, more topics will be introduced.
Another thing is that each lesson is planned to take less than an hour so a student can work through but I'd say each part will take 30 to 50 min depending on how well someone processes information.
I like that each lesson has several topics with a video to explain the material, followed by an activity. Just glancing over the material, I learned things and I want to spend time exploring this in more detail and even taking the class. I want to create my own animated movie after checking this out.
The material covered by the first lesson is geared for everyone but after viewing it, I think it would really be good for grades 5 and above. Just think, if you need something for your kids to do this summer, they could work with this. If you are home schooling, this provides a strong link to real life math.
Have a great time exploring.