I am teaching math to 3rd graders and after doing an assessment of their math skills more than 75% of them could not understand subtraction using 2 digit numbers. When I posed a 3 digit subtraction problem they looked at me like I was a tourist from another land using a translation dictionary to ask where the bathroom was. I'm currently looking for other ways to try and pass the information over to them since I am new to this. However, I am dismayed and troubled over their skills. Shouldn't they understand this by now? or is this level of understanding normal? Thanks.