Email your AART back and ask if you can see the slideshow presentation they all do around the November timeframe on level IV. Those presentations include 2 or 3 "ideal" work samples along with a what-not-to-do that is super helpful.
Though don't be fooled, I think 1-2 of the work samples are by kids who are older than 2nd grade, so don't worry if the samples look advanced.
I find
this site to be a good source of the kind of math problems the AAP.
For language arts I have my kids do Reflections in 2nd grade and we use that. We include both the entry and the artist's statement.
Our AART says to have your kid provide a write-up with the sample explaining their thinking. 00:35 has a good idea, but our AART says to take it a step further and transcribe/have your kid type the explanation. Her words, "The committee doesn't want to hear from you, they want to hear from your child."