Adding Fractions the Singapore Way!

I'm getting lots of fraction questions lately...must be close to testing time!  There are so many important teaching points here.  I think this addresses that we can only add like things together.  If they aren't alike, we have to find a common term.  That's true in first grade.  When we add circles and triangles, first we have to find the common term, shapes.  In fractions, if our denominators aren't alike, we have to find the common term before we can add them!

How does this address the common core standards?  What extension questions are you asking?  Can you step back and bit and teach them to persevere?