Front Row is an easy and great tool for classroom differentiation!
The free resources in Front Row are enough to give data on your students current levels. Teachers will need to collect data weekly and store in a word document to see growth if only accessing free site. The level of differentiation that can be acheived in your classroom using the free site is as good as websites that cost $100 per student! The only downfall is the lack of spiral review and assessment to see if student retains the skills learned.
How I Use It
I use Front Row Math with both advanced learners and students below grade level. Even visiting this site once or twice a week has been beneficial for my students.