A good thing about homeschooling is that you have a first row seat to the intent of the child. Seeing my kid try and still not quite make it perfect does sway my grading. Will I give an "A" when every problem is wrong? Not likely. But I would give a second chance to correct it before marking it in the grade book. I might go on and take a week or a month to repeat the lessons, this time more indepth, until we retake the failed work and permanently add it to the average.
Doing school at the Zoo.