Substitution (…and Continued Fractions) ¶
Sam Shah, with a great mechanism for substituting an expression with an equivalent variable: use a note card with the expression on one side and the variable on the other.
I emphasized that that card itself represented the value of that fraction. The front and back are both different ways to express the same (unknown) quantity we were looking for.
THAT FLIP IS THE COOLEST THING EVER FOR A MATH TEACHER. That flip was the single thing that made me want to blog about this.