Using Java applet dynamic figures in teaching mathematics

Examples for "drills", exploring and conjecturing

Some suggestions on how interactive dynamic figures can be used in teaching and learning mathematics


Martti E. Pesonen
Department of Physics and Mathematics
University of Joensuu
P.O. Box 111
80101 Joensuu
Finland
email: Martti.Pesonen@Joensuu.Fi
This page:
http://www.joensuu.fi/mathematics/MathDistEdu/Borovets2008/index.html

Learning and understanding even the most basic abstract mathematical concepts and the relations between such concepts is far more challenging than becoming skillful in applying cook-book algorithms or learning to use standard procedures that aim to predictable solutions. Especially difficult is to learn-away the vague and defective conceptions that the students have adopted in the earlier stages of their studies and tend to stick to as long as possible. One crucial concept in pure mathematics studies is function. which KESKEN
Since just telling how they should change their view is very seldom enough

1. Important computer tools

A. Computer algebra systems: Maple, Mathematica, Matlab (with extensions), Maxima(free and open source)

Computer algebra systems are programs that support manipulation of expressions and functions, handling of numeric data and plotting graphs in 2 and 3 dimensions. There may be some more sophisticated facilities like programming, animations, simulations and even direct interaction using some graphing parameters.

B. Dynamic Interactive Geometry/Algebra: Cabri Geometry (also 3d), Cinderella, Euklid DynaGeo, Geometer's Sketchpad, GeoGebra(3d promised to come, free and open source)

Dynamic geometry programs provide us with high level of interactivity, but do not require programming skills when used for "pure" geometric constructions. Even children - perhaps exactly them - are ready to start from scratch and find amazingly quick applications of this graphical facility. The basic objects are points put on the screen, and they can be draggable or fixed, visible of hidden. Second level objects are other points, segments, rays, lines, circles, arcs etc. defined using the basic points. New objects depending on the previously defined ones can be created using tranformations like translation, reflection, rotation and dilation, and also defining the intersections of existing objects, e.g. the points common to a cirle and a line.
More convenience is achieved if also more complicated objects like triangles, quadrangles etc. are available.
If algebraic dependencies are allowed to be used in defining new objects, one can also plot parameter and variable dependent graphs.
When the free points are moved, the whole construction changes, keeping the defined relations invariant.

GeoGebra is a dynamic mathematics software for education in secondary schools that joins geometry, algebra and calculus.
On the one hand, GeoGebra is a dynamic geometry system. You can do constructions with points, vectors, segments, lines, conic sections as well as functions and change them dynamically afterwards.
On the other hand, equations and coordinates can be entered directly. Thus, GeoGebra has the ability to deal with variables for numbers, vectors and points, finds derivatives and integrals of functions and offers commands like Root or Extremum.
These two views are characteristic of GeoGebra: an expression in the algebra window corresponds to an object in the geometry window and vice versa.

C. Course Management Systems: Blackboard/WebCT, Stack, Wims, Moodle

There are numerous general purpose computer systems for supporting course management. This means: delivering course materials in electronic form, keeping track of students and their online-work like returning essays and online-tests, allowing group work over the system, discussion forums, chatting, etc. The systems runs on some server and it can be accessed from anywhere.
The user interface is usually arranged on web browser basis, which usually should allow dynamic figures to be embedded on any tool on the system.
Moodle is a free course management system, open source software package designed using sound pedagogical principles, to help educators create effective online learning communities. The author uses Moodle mainly for offering to his students online training materials and small-scale online-tests concerning the definitions of basic mathematical concepts like relation, function and binary operations in the general (Bourbakian) sense that is needed in learning the axiomatics of abstract algebra and linear algebra.

2. Three examples of the use of dynamic figures

A. Drilling
 

Own course pages (in Finnish): Introductory first year University course in Mathematics, Linear algebra and Discrete Mathematics.

Pedagogical research focus: fundamental abstract concepts in mathematics (relation, function, binary operations)

Binary Operation (Internal within a set, External with a scaling set)

Linear Functions (Basic in the Plane, Eigenvalues)

Complex Numbers (Complex 2nd order polynomial)

Function f, f(z) = z2 + bz + c, with zeros z1 and z2.

Double point if the center point  1/2 (z1 + z2) of the segment joining the zeros of  f is inside the circle
Complex 2nd order polynomial starting from the zeros

Had to be proved:
Proof (pdf)

Eric Lehman and me in Caen in December 2007.