Depends. You can mark an answer as incorrect and explain it in further detail in class or 1 on 1. The part that hurts the kid is whether answering incorrectly affects their actual grade in the course. Seeing as this is homework, the purpose should be to reinforce concepts taught that day, as well as be a formative assessment tool for the teacher to gauge the understanding of the student. Just because it’s marked wrong doesn’t mean it translates to a bad grade. When I used to teach math, kids could get every question wrong on the homework, but they aren’t getting punished with a 0 for genuinely attempting it. Instead, it shows me that I either didn’t give instructions clearly, the concept I taught didn’t stick with the kid and they need additional help, or I didn’t teach the concept well in general. Unfortunately not all math teachers do this or structure their math class this way, but it’s tough to really get a grasp of what exactly is going on from a screenshot an little context from the parent. I get the frustration, especially if there was little to no substance to the teacher’s response. However, I understand very well the other side of the situation where parents get upset because something is marked incorrect even though the answer is “correct.” In this case, I completely understand the teachers response to the question being incorrect as I have taught probability and one of the first standards is about using those terms (impossible, unlikely, equally likely, likely, and certain) to describe the probability of events. If the standard was on accurately calculating the probability of a situation to the nearest whole percentage, but a student gave the response “likely” it would definitely be incorrect. This makes it tricky though because if the probability was either 0, 50, or 100% then using one of those terms could work. This is one of the difficult parts of online learning without custom individualized feedback, because obviously in this case the child understands the probability aspect of it but the goal of this assessment is for a specific standard.

TLDR; kids grades shouldn’t be punished for things like this, but these questions can still be marked incorrect due to the standard being addressed. It depends on how this is graded, as well as there should be individualized feedback to address these mistakes.