I discovered that:

Each kindergarten class had 35 tens rods.
Each first grade class had 70 tens rods.
Each second grade class had 140 tens rods.  

This pattern continued all the way through eighth grade.  

I also know there are:
4 classes in every grade k-5
3 classes in both grades 6 & 7       
2 classes in grade 8       

1. How many tens rods are in the entire school?                

2. Challenge: How many hundreds flats could you trade all the tens rods for?