Plausible distractors in MCQs

In the section about [formative assessment and MCQs](https://carpentries.github.io/instructor-training/02-practice-learning/index.html#using-formative-assessment-to-identify-misconceptions), should we consider that the plausible distractors depend on the strategies that are taught? In our example, we assume that the child was taught to "carry" the number in the tens place. Not everyone is taught this way.

For example, I'm currently working with students who learn to round numbers up/down to make numbers that are easy to add in your head, and then add/subtract the difference.

So for this they would:
* round 27 --> 30 (+3)

Then add:
* 30+15 = 45

Then account for the difference:
* 45-3=42 (-3 that you added before)

So if this was the strategy taught, plausible distractors might actually be

* 48 (you added the rounding difference instead of subtracting it)
* 45 (you forgot to subtract the rounding difference)

I know we can't make this section complicated but I do want to account for differences in early math curricula across generations and geography. To consider the plausible distractors we offer in the curriculum, trainees have to think about arithmetic in a way they may not be used to.

Start with the formative assessment and MCQs section linked in the issue, especially the discussion of plausible distractors. Review the existing arithmetic example and decide how to acknowledge that distractors depend on taught strategies; done means the section reflects this variation without becoming unnecessarily complex.

Written by the indexing model from the issue text.