[kfrang]

Page 10 of the Fraction Progression document is the following statement (which is also included in the videos on Illustrative Mathematics):
In grade 4, students calculate sums of fractions with different denominators where one denominator is a divisor of the other, so that only one fraction has to be changed. 

The progression document then gives an example of adding fractions with denominators of 3 and 6 (not 10 and 100).

In the actual CCSS on page  31, the footnote says
Students who can generate equivalent fractions can develop strategies for adding fractions with unlike denominators in general.  But addition and subtraction with unlike denominators in general is not a requirement at this grade.

I am wondering where in 4th grade teachers see that they are responsible for addition of fractions where one denominator is a divisor of another.  I only see 4.NF.3a which could extend to this, but does not say anything about explicit about divisors that are multiples of another.  Although I agree with the footnote, the supporting materials are very specific about grade 4 that does not seem to be included in the actual standards.  I might just be missing something.

Thanks in advance for your time.

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