A C grade at GCSE mathematics is usually considered a minimal passing grade.
Typically, a student who can interpret and answer simple ratio and proportion questions will reach a C grade.
I would expect a student who scores lower than a C grade to have some significant difficulty in answering this type of question:
"Here is an ingredient list for 2 cakes; write an ingredient list for 5 cakes."
As you might understand, students below this level are excluded from almost every skilled career.
In my experience, there are very few students who are intellectually incapable of reaching this level, but there are many (37% of all students in the UK) who don't reach this level because they don't have appropriate educational opportunities.
Universal access to good education is not a solved problem.
Typically, a student who can interpret and answer simple ratio and proportion questions will reach a C grade.
I would expect a student who scores lower than a C grade to have some significant difficulty in answering this type of question:
"Here is an ingredient list for 2 cakes; write an ingredient list for 5 cakes."
As you might understand, students below this level are excluded from almost every skilled career.
In my experience, there are very few students who are intellectually incapable of reaching this level, but there are many (37% of all students in the UK) who don't reach this level because they don't have appropriate educational opportunities.
Universal access to good education is not a solved problem.