Learner directed tours, like the five collections of science resources offered by Rader, are great tools for differentiating activities within the classroom.

Rader has been producing useful self-study lessons and quizzes for younger learners for quite a while. 

The five websites to visit are...

http://www.biology4kids.com/

http://www.chem4kids.com/

http://www.cosmos4kids.com/

http://www.geography4kids.com/

and http://www.physics4kids.com/index.html

They are good resources for science and/or Family Learning Practitioners to link to a class/course web page or blog so that learners, with their guardians and parents can study and test themselves outside of the learning environment.

Each 4 Kids resource takes learnerss on tours of different sub-topics. After each stop on the tour there is a quiz that learners can take to test their understanding of each topic. Along with text and image information there are some short videos about different concepts along the tour.