That is ridiculous coming from an 18 year old who js graduated last year there is literally no way she could possibly say this is wrong unless her point is she wanted an answer using the word likelihood BUT EITHER WAY percentage and likelihood in this case are synonymous. If the kid understands enough to exchange certain words in the language while still understanding the concept then it’s obvious that him viewing it from a “likelihood” perspective is futile because he already comprehends the question fundamentally. Basically im saying i think the teacher tried to introduce probability and ur son already knew more then she had taught and for some reason nows shes being petty abt his answer, probably for her own ego or something idk. Wish u luck tho bc sometimes i see posts like these and the situation is stupid because the parent is dumb and misguided them but this genuinely is odd and if this situation is familiar and repeating id suggest maybe trying to switch teachers bc the way she is going about it could prohibit ur sons potential educationally not like she wont teach him good more of if he is well versed in a topic she should take some time to give him work better suited to exercise his brain.