It's depressing but giving people "s = d / t" then asking questions like "Bob travelled for 2 hours at 50 mph. How far has Bob travelled?" is still tricky for some people to work out. We don't want people to learn formulae. We don't particularly need people to do mental arithmetic. We want people to understand problem solving and gathering information and relationships between different bits of the formula. See also the viral video "meaning of MPH" ( [this video] ) There's some unpleasant "HURR DURR GURLS ARE STOOPID" in some videos (and don't for the love of god read the comments) ( [link] )
Viral video showing students struggling with the meaning of speed.
How do you mean "subjective"? There is an objective answer to the question "how many golf balls can fit in a double decker bus" and while I suppose you could call it "trivial", being able to make that kind of estimate efficiently really is an important skill for programmers (and scientists, and engineers) to have. That said, this is another FizzBuzz sort of test, and should not be made unnecessarily complicated. This is what you're trying to filter out: [this video]
Why do you assume that students know what speed is? Have you seen this video? [this video] The problem here is that she don't know what speed is. She knows a lot of formulas, but not what speed actually is. That is a typical student, if you add speed in a formula you will make them confused and the problem will get harder.
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