I agree with Steve's non-negotiable list! As I read through the various posts I can't help but see how the curriculum in mathematics has gotten to be a mile wide and an inch deep!
As we all add to what we feel should be part of the non-negotiable list...I wonder if we can make the connections from the very basic skills of the non-nogotiable list to the additions we are asking to make?
For example, having students learn to read/measure with a ruler. This can be connected to students working with fractions on a number line and seeing fractions as true numbers and not just something to fear. If students can work with fractions on a number line, they will be able to use a ruler (which is just a number line with fractions)!