[teiferer]

Maybe it's because I'm old and things are different now, but back in the day, first year of primary school was when everybody learned to read. Some kids already knew some (incl. me), and that didn't necessarily make life easier for them since some parts of class they were then bored. Well, you learn to deal with it.

It's not like such situations never occur in adult life. I often find myself in work meetings where colleague A explains something to a group of 10 people to get everybody on the same page, and there are often one or two folks who already know this stuff and are obviously uncomfortable for those 10 min of intro. Clearly, they never learned how to deal with such a situation.

[JohnBooty]

    since some parts of class they were then bored. 
    Well, you learn to deal with it

It's a crucial life skill.

I'm highly doubtful that forcing young kids to be bored (by making them progress/learn slowly, when they could be learning more) is the best way to do it.

[teiferer]

Oh I'm not disagreeing. Forcing boredom is not the way. But preventing it at all costs may not be either.