Believer in gaps here! Maybe my dd isn't gifted enough, but she still has trouble with tallies. She skipped K where tally marks are apparently big business, and now is in 2nd grade with 3rd grade math. She STILL cannot do tally marks! It's a mental block or something.
Is it that she doesn't understand the concept--a real gap!--or that she doesn't *like* to use tally marks? It seems to me that she's just choosing another way to solve the problem, and that isn't so much a gap as a matter of preference. Provided she gets the concept and can still solve the problem, I don't see it as a big issue.
I think you're right that this is one of the reasons teachers worry about gaps, but I also think it's rather unnecessary. Is your DD going to be unable to progress in math because she'd rather write numbers than tally marks? I don't think so!
