Need a tutor? I am now a private math tutor and computer science tutor! Please visit my Web site for more information.

--Jon Dreyer

Mr. Dreyer's Math Toys

These are some math toys I built with GeoGebra for my classes. They require Java. Sometimes you may need to reload the page a few times to see the buttons which launch the toys. Have fun!

Algebra

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Slope-intercept form

This graph shows y = m x + b. Use the sliders to adjust m and b. It may be easiest to try to set them to "friendly" numbers. What do m and b represent on the graph? What are the coordinates of the red and purple points in terms of m and b? Why does each of those points lie on the graph of y = m x + b?

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Point/slope form

This graph shows yy0 = m (x − x0). Use the sliders to adjust m and x0 and y0. What are the coordinates of the red and purple points in terms of m, x0 and y0? Why does each of those two points lie on the graph of yy0 = m (x − x0)?

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Standard form

This graph shows A x + B y = C. Use the sliders to adjust A, B and C. What are the coordinates of the red and purple points in terms of A, B and C? Why does each of those two points lie on the graph of A x + B y = C?

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Absolute value functions

Hit the button on the right to see a graph of y = a |x-h| + k. Play with the sliders to change a, h, and k. For example, when a=-2, h=3, and k=4, what is the slope of the right "piece" of the function in terms of a, h, and k? What is the vertex? What values of a make the vertex point down? Up?

Geometry

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Hypothesis about angle and segment trisection

In class, some students hypothesized that in an isosceles triangle, rays drawn from the vertex to trisectors of the base trisect the vertex angle. In this experiment, drag the vertex to see the angle measurements change.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Types of triangles

As you move the triangles around, the equilateral, equilateral, equiangular, isoceles and right triangles (green) stay true to form, while the others (red) may change

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Beyond CPCTC

From section 3.5 (p.125-126.) Sample problem 1.

Jon Dreyer