Don't run with swords in your ...

Don't run with swords in your mouth!
 Dan Meyer

Quotes from the same author

We're no longer intimidated by math, because we're slowly redefining what math is.
 Dan Meyer
Students need to decide, 'All right, well, does the height matter? Does the side of it matter? Does the color of the valve matter? What matters here?' - such an underrepresented question in math curriculum.
 Dan Meyer
The physical five oranges goes up the ladder to the picture of the five oranges which goes up to the representation of the five oranges as a numeral. This points in the direction of a definition of abstraction: when we abstract we voluntarily ignore details of a context, so that we can accomplish a goal.
 Dan Meyer