Is this discrimination?

[Citymum7676]

Name changed for this post

Here is a situation that happened in the class (maths, y6, private school).
Children asked to draw a resort. I think the topic was space and proportions.
Child A draws fountains and hills.
Teacher asks: so, what are your ideas?
Child A: fountain and hills
Teacher: that’s not a good idea
Child B: sea
Teacher: brilliant
Child C: fountain!
Teacher: that’s an amazing idea! Fountain!!

In the end of the class: you should do this and that, not some kind of rubbish like your work, looking at child a. Work was not submitted to the teacher, they were only discussing ideas.
Child A felt discriminated. Child A is of different race whereas child B and child C are white. After the class child A’s friends told him that his ideas were the same so why was the teacher favoriting other kids? This teacher was substituting for a couple of classes and does not teach this class normally although is a head of maths.
Mum of child A (me) very very hurt to hear

My kids are small but surely calling an 11 yo's idea "stupid" is a bit much. "You can think of a better one/not quite right / no hills in this resort ()" would have been better.

I would be very sad if my boss called an idea stupid!

To me it sounds like a problematic question that could cause discrimination issues, but not just or necessarily racism per se. What experience or knowledge of resorts do children in the class have? My two at that age - I've no idea what they would have thought a resort might include. Even now as teenagers I'm not sure, because not only do we not go to resorts but their interests are such that I wouldn't be surprised if the younger one in particular had little concept of what a resort might be. He has stayed in fancy hotels a couple of times on choir tours in the past though ...

I'm reminded of something that happened to my sister in year 7 and really annoyed my mother. For an English exercise they were asked to write a chat show script. Now, we were in Australia and chat shows there were decidedly not something anyone watched in our house. But, over the Christmas holidays before the start of that year, we had visited our granny in the UK. And had watched a bit of Terry Wogan (this was in the 80s). So my sister's exercise drew on that experience. Her teacher utterly rubbished her work as completely wrong and not how chat shows worked ...