I'm glad you liked it Melisa!

Rusczyk has several articles posted on the AoPS website. You can also get videos for the Pre-Algebra class on the website for review and a feel of the AoPS style. I would hazard a guess that it is far harder than the kind of math your son may be used to doing! We also use Alcumus (the online program with AoPS) extensively and it may be worth having a run through the problems over the summer.

I hope you have success with your meeting and you're able to advocate for Algebra placement for your DS!