Struggling in a few subjects is one thing. My Pre-algebra teacher passed me because my father had died when I was in her class. She took the act of compassion that lives with me to this day.

As for 3rd grade we had kids who couldn't read. IMHO compassion or social promotion, not be able to read and passing them was not doing the child any favors.

English and Pre-algebra we had the fundamentals even as these were a challenge.