This site contains a JavaSketchpad applet for changing the parameters of a parabola presented in standard form. The applet allows the user to drag the points labeled "a", "h", and "k" to change the respective values in the equation y=a(x-h)^2+k and see the effect of these changes in the graph. It contains instructions for using the site, scroll bars for the parameters, and the movable graph.
Type of Material:
This is an interactive JavaSketchpad Applet.
This site can be used for students to explore how changing the parameters of a quadratic affect the corresponding parabola. It is an activity that can be worked as a very short introduction to parabolas. This applet can also be used as an introduction to function transformations.
A JAVA enabled browser is required.
Identify Major Learning Goals:
The student using this site will learn how the parameters of the parabola y = a(x h)2 + k are related to the quadratics graph .
Target Student Population:
Intermediate and College Algebra students.
Prerequisite Knowledge or Skills:
Basic knowledge of the equation of a parabola.
This site allows the student to use a slider to manipulate the parameters and quickly understand how these parameters affect the graph. Students are asked to find a parabola that passes through two given points. They will realize that more than one parabola passes through two given points. They will also physically and visually explore the shifting of the graph caused by changing two of the parameters and the stretching effect of the other parameter. In just a few minutes the student will get a hands-on understanding of these concepts.
There is no background information given that discusses the geometry of the parabola and algebra of quadratics or the meanings of a, h, and k. A title, contact information, and links to a main page and resources are not available (http://lasi.lynchburg.edu/peterson_km/public/old/).
Potential Effectiveness as a Teaching Tool
Because of its simplicity, the student will be able to achieve understanding of the intended learning goals in just a few seconds. This applet could be used effectively by an instructor to demonstrate the equation-graph relationship in a classroom setting.
The instructor will have to guide the students towards the purpose of the lesson.
Ease of Use for Both Students and Faculty
The site is very simple. It develops just one small concept with easy-to-use sliders. The student will need no coaching on how to use the applet as there are well written instructions.
The user is asked to find a parabola whose vertex is at the point (2, 1); however, the reviewers were never actually able to achieve an exact vertex of (2, 1). This could be quite frustrating for an inexperienced user of JavaSketchpad applets or one who is not sure that an approximate vertex of (2,1) is sufficient for answering the question posed.
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