Before getting upset, ask your child some questions

 

What was the film all about, science documentary or social commentary?

Why do you think the teacher asked such a question?

Did the teacher answer the question?

What's the reaction of the white students?

What's your (the child's) answer to the question?

 

Presumably, the teacher wanted to point out "white privilege." More questions can follow that.

 

Another thing of concern is the quality of the science education your child receives. Competent teacher does not need this kind of distraction.