Fix title (Thanks @JimBrennan!)
(x + h) -> (x - h) (Thanks @smenks13!)
On checkAnswer event trigger, pass whether or not the attempt qualifies as 'fast'
New exercise: Z-scores 1
@beneater changes and whitespace
Add exercise: Multiplying expressions 0.5
Don't immediately make any problem right from khan-exercises unless you're in practice mode -- otherwise, just send a 'ready' event
Add exercise: Solving quadratics by taking the square root
Fix some silly sign errors
added z to equation in hints
Implement @nsfmc's awesome idea of scrolling up before animating
More work trying to turn khan-exercises into a black box that behaves more like: 1) khan-exercises.render(exercise), 2) fires 'starting' event, 3) fires 'rendered' event. It's not there yet and I probably won't get it all the way, but that's the direction for power-mode.
Workaround for coefficients of 1 or -1
Use plus() to handle coefficients of -1, 0, and 1
new markup and commission word problems and added to the word problems library
More work on being able to pass UserExercises into khan-exercises dynamically.
Merge pull request #15071 from beneater/quadratic-sqrt

Add exercise: Solving quadratics by taking the square root
Merge pull request #15048 from beneater/mult-expr-0.5

Multiplying expressions 0.5
Merge pull request #14889 from beneater/graph-parabola

Graphing parabolas!
Merge pull request #15028 from smenks13/zScore1

New exercise: Z-scores 1