Very good, and good for Heinlein. As a former math teacher I have an observation.
Most students can “get” algebra, it is formula driven and learning a few rules can solve many problems. (Word problems are more severe because the problem does not define which formula to use.)
What really determines who should go to college however is not algebra, it is Geometry. That is the best explanation for why two math courses used to be required for college entry. (State or University)
I believe this is because Geometry really uses logical thought and sometimes requires multiple starts at a solution. At any rate, geometry separates the thinkers from the plug and crank types who can pass algebra with sufficient effort.
I do not know why People of Color have problems, but certainly some of them want short cuts and when faced with a problem that requires hard work, they likely find something else to do. (One of my students tried modifying the test answer and then asking for my re-evaluation. Only I could see the correction that was made. Opps — parent conference. And the parent sided with me.)
——Word problems are more severe because the problem does not define which formula to use.-——
boy isn’t that the truth
I enjoyed the 8th grade arithmetic that was mostly word problems
When i struggled with algebra and then learned to like it, I realized the word problem arithmetic was not the way. Equations re the way to go