Where can you get academic worksheets for special ed high school students that is age appropriate yet on a 1st grade level?
It really depends on what subjects you're looking for.... and what you are looking for when you say age appropriate.
One site with lots of elelemtnary worksheets is: http://www.superteacherworksheets.com There are math worksheets, grammar worksheets, printing/handwriting worksheets, etc. Perhaps those can help you.
There are many other sites on the Internet as well. I'm sure a few specific Google searches can revel some excellent ones.
GOod luck to you!