I like to think of math on a continuum. I don't teach 6/7, but
when I've taught split grades, I look at the main concept
and how 7 differs from 6. For example, in grade 4/5, the 4s
need to know decimals to a tents while 5s do decimals to
the hundredths. So, I would teach decimals with everyone,
but retire 4s to do work to the tents and 5s to the
hundredths. There are some concepts that a very different
between grades but most work on a continuum.
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