I am not convinced that any of the above posts are correct. American grading systems are generally along the lines of a ten point scale. I.e. A=100-90%, B=90-80% etc. Foreign systems tend to differ from this. For example, in England, the accepted system is (in universities, at least) 70% or above is an A, 60-70% is a B, etc. It is still a ten point scale, but reduced. The thinking behind this is that it gives those students who really know over and above what they need to the recognition that they deserve. I think Canada might be along these lines too.
For example, I went to an English university for a year. I achieved averages of about 75-80% in my courses. On return to the US, the people who transfer the credit tried to tell me that this equated to a high C average, and wanted to give me C grades. I explained their mistake, and showed them proof of the grading scale, and I received the A grades I earned.
I would suggest that you accompany your Canadian grade report with an official grade scale from your school, showing what grades your percentages equate to. This should solve the problem (unless your school uses a US style 10 point system, in which case, you might be in trouble
).
I get the impression that the US method of grading is an attempt to make their students look better by 'raising the bar'. It makes an A grade student in other countries look like a C grade student here, although they are equivalent. The American system is a product of a very structured higher education system, where students are taught, rather than students learning for themselves (e.g. like an extension of high schools instead of a true university). Basically, a student is considered very good if they memorize the required material in the US. Elsewhere in the world, students are considered good if they use their own resources and minds to adopt the material. Go figure...
Bottom line - your percentages might equate to grades that are not on a ten point scale. Get a Dean or Professor to officially write down a grade scale for your school, and stick it with your grades.