If he has 70% on pre-alg assessment with gaps, you might want to call them and ask what they suggest. I talked to a higher level(?) person I think, who recommended that DD actually finish the pie completely before I moved her up. Something to consider.
However, she was bored so I did not take the advice and moved her up manually myself, she was at about 95% finished with pie. I then manually sent her an assessment before she even started to make sure she picked up anything she may have missed.
Just for giggles I manually moved up ANOTHER level and delivered her an assessment and discovered there is a ton of overlap between levels. I'm pretty sure pre-alg starts at level 4, but for SURE there is pre-alg at level 5.
I do LOVE that the program is extrememly thorough with regard to material included. I do NOT believe they cover as much at school, no matter what they like to tell me.
One tip I discovered late. DD loves to master things, she's a little pathological about it. I asked her to NOT go on to master, that way it does come up later for review. Otherwise, it doesn't. I find this helpful(not sure she does!) because then when I see her correctly do the problem weeks later, I feel more confident that she does have it down concretely.
I also use the Singapore workbooks to go back and for review and make sure she can correctly complete problems on paper since this is how most testing is still delivered.
HTH
Neato