Resources:
- Awareness of Pre-algebra concepts (Grade 3-8) by Lois Cullipher
http://ericir.syr.edu/Virtual/Lessons/Mathematics/Algebra/ALG0001.html
- Factoring Large Numbers (Grade 7-8) by Tim Olson
http://ericir.syr.edu/Virtual/Lessons/Mathematics/Arithmetic/ATH0005.html