4 ms·

> This is a reasonable problem to teach students about for like 1 week at age ~10. I'm afraid you have a completely unrealistic expectation of the median stude

> This is a reasonable problem to teach students about for like 1 week at age ~10. I'm afraid you have a completely unrealistic expectation of the median student (which is reflected in your other comments as well). I have taught hundreds of students and I would think a handful of them could answer this at age 10. This type of question first appears on the Khan Academy in Grade 7, i.e. targeted at 12-13 year-olds. There is a significant body of prerequisite work in the earlier grades, some of which is limited by what is developmentally appropriate. Students will need dedicated practice to recall this and most won't remember it after seeing it or mastering it on one occasion. It needs to be supported in the rest of the curriculum. You might be able to intensively teach it earlier, but it is hardly worth it, because they will completely forget when you intensively teach the next topic. Many 15-year-olds will continue to struggle with this and, if they are well-supported, might be taught it as a step-by-step procedure in order to best score marks in the exam they need to. These students are unlikely to finish without a good concept of what they were doing - and might be more likely to pick it up as adults out of necessity.

jacobolus 6y ago
«Add 7.1% sales tax to the $19.95 ticket» (or whatever) is a 1-step (or generously 2-step) arithmetic problem, of the kind most students in many parts in the world learn to understand conceptually at age 6–7 with no problem. It additionally involves multi-digit multiplication, of the type people typically learn by about age 9–10 (?). If students have not practiced solving problems enough to handle combining these things until age 13, and many are still struggling with it at age 15 (with a calculator!), that’s a serious indictment of the entire education system.
- throwaway2245 6y ago
  I checked some well-respected national curriculums. Singapore was the only one I found where percentage increase is introduced earlier as a national standard. It's mentioned in the curriculum for Singapore Primary 6, i.e. 11–12 year olds, for students in the higher of two streams for mathematics.

jacobolus 6y ago

«Add 7.1% sales tax to the $19.95 ticket» (or whatever) is a 1-step (or generously 2-step) arithmetic problem, of the kind most students in many parts in the world learn to understand conceptually at age 6–7 with no problem. It additionally involves multi-digit multiplication, of the type people typically learn by about age 9–10 (?). If students have not practiced solving problems enough to handle combining these things until age 13, and many are still struggling with it at age 15 (with a calculator!), that’s a serious indictment of the entire education system.

throwaway2245 6y ago
I checked some well-respected national curriculums. Singapore was the only one I found where percentage increase is introduced earlier as a national standard. It's mentioned in the curriculum for Singapore Primary 6, i.e. 11–12 year olds, for students in the higher of two streams for mathematics.