Applets Directory


Henri Picciotto

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.


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

Completing the Square

Complex Number Arithmetic games

Constant Sums, Constant Products

Difference of Squares

Factored Form of a quadratic

Multiplying binomials

Off and On, understanding linear inequalities

Squaring a Binomial

Stairs, slope puzzles

Trinomial multiple representations


Signed Numbers games

Pie Slices
The Well-Chosen Rectangle

Doctor Dimension, exploring rate of change

Function Diagrams, a parallel axes representation

Sine Curve

Iterating Linear Functions:
with a table
with linked function diagrams
with a 'cobweb' graph

Iterating `f(x)=rx(1-x)` in two representations

Bifurcation graph for `f(x)=rx(1-x)`


Area of a Circle


Geometry of the Parabola

Isometries (Rigid Motions)

Only four kinds

Making Triangles


Pythagorean Theorem

Soccer Angles

Sum of the Angles in a Triangle

Symmetry with Pattern Blocks

Tri, Tri Again (inscribed circle iteration)

Virtual Manipulatives

Virtual Circle Geoboard

Virtual Geoboard

Virtual Grid Paper

Virtual Pentominoes

Virtual Tangrams


Parallelogram area

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.