Since my kids are older (J.H and H.S.) they take tests if the curriculum provides them - i.e. TT math, Apologia Science General and Physical, Spelling Power,etc. If they get just a few wrong I go over them and when they've figured it out I give them an A. If they've gotten a ton wrong they have to redo it until for the most part they "get it"... It slows us down some but it's worth it overall. From there I don't make out a report card but just add them to their portfolio and will use the overall grades for my 14 year olds transcripts.
We don't do grades. I think he's about a B+ student in just about everything, except maybe writing - maybe a C. I am hoping to have him take the SSAT this spring. It will give us a good indication of how he fits in with other kids as it is nationally normed and proctored by a private school. I guess we will have to take a few weeks to prepare for it though - he's never taken such a formal test.
We didn't have to keep grades on file, so we really didn't worry too much about grades. Provided they did well in tests, we were comfortable with their progress. Plus (and much to our children's chagrin!), I'm someone who likes to ask random questions when we're driving somewhere to see whether they understand the material. With sufficient probing, it becomes clear very quickly if there are problems. Every year, we had our children take a standardized test (BJU, I believe), which would have revealed any areas of weakness.