Applets are small, single-purpose computer programs, usually available on the Web through a browser. For this site, I built the applets in GeoGebra, with the goal of making various mathematical ideas more visual and more interactive. (Tech note: how I build the applets.)

However you cannot expect them to teach the concepts they illustrate! They are most effective if they are part of a multidimensional pedagogy that gets students to engage intellectually rather than watch passively. (Blog post: Seeing is Believing?)

You can use the applets online, and/or download the corresponding GeoGebra files and modify them to better fit your needs.

Each link below is to a single applet, or to a launch page with links to several applets, or to an article where applets provide the illustrations.

## Algebra

Changing a, b, c in `y=ax^2+bx+c`

Complex Number Arithmetic games

Constant Sums, Constant Products

Factored Form of a quadratic

Off and On, understanding linear inequalities

Stairs, slope puzzles

Trinomial multiple representations

## Arithmetic

Signed Numbers games

- Fractions
- Pie Slices
- The Well-Chosen Rectangle

## Functions

Doctor Dimension, exploring rate of change

Function Diagrams, a parallel axes representation

- Iterating Linear Functions:
- with a table
- with linked function diagrams
- with a 'cobweb' graph
Iterating `f(x)=rx(1-x)` in two representations

## Geometry

Only four kindsSSASum of the Angles in a Triangle

Tri, Tri Again (inscribed circle iteration)

## Virtual Manipulatives

## Other

Pent, a two-person strategy game

Penumbra, some of the geometry of eclipses

Spirograph, exploring symmetric figures created by a circle in a circle

As I create more applets, I'll try to remember to add links in this directory.