Desmos
I love Desmos, it is a great free on-line tool that provides graphical analysis of mathematical formulas. I teach an applied calculus course and use Desmos all throughout the semester to help drive home concepts.
Slope Intercept Form.
Notice the equation y=mx+b, where m is the slope and b is the y-intercept. Adjust the m & b sliders and observe the line.
Circle
Here is the equation for a circle with its center at the Origin. Adjust the radius and observe.
Circle with offset center
Adjust the h & k (horizontal and vertical) offsets and the radius.
Parabola
Adjust p
Parabola with offset Vertex
Adjust h, k, & p
Sine wave
a represents amplitude
b represents frequency
c represents phase
They say math jokes are a sin of madness…
Why can you never trust a math teacher who uses Desmos? They are always plotting something!