OGCPS

One Graphing Calculator Per Student

Keywords

OLPC OGCPS

Background

Starting this year in schools across the world, the use of graphing calculators is being incorporated into the education syllabus of mathematic subjects such as algebra, trigonometry and calculus. Graphing calculators are more expensive than the already costly scientific calculators. And this has raised issues of costs and funding, as well as the logic of burdening students with a US$100 device that's never use after a semester/term.

Various proposals such as student loans, equipment sharing and rental have surfaced and are being tossed around. To paraphrase One Laptop Per Child (OLPC) association's message - Students can do a lot of self-learning, especially when they don’t have to leave the (loaned) graphing calculator behind in class. Although PC-based graphing calculator programs exist, the cost of the software licenses and notebooks may still exceed the budget of public schools and disadvantaged students from low-income families / developing countries.

Mission

The objective here is to create a low-cost introductory & disposable graphing calculator for the educational use of schools and students who may have difficulty, are unable or may not wish to acquire a stand-alone feature-laden graphing calculator.

Why A Mobile Phone?

A common handheld device found these days is the mobile phone, and most students have one - even if it's an entry-level model. Some of these may even be used or refurbished phones. In keeping with the goal of affordability, the mobile phone graphing calculator should not be dependant on premium features such as S60/UIQ Symbian or Windows Mobile that are available only on high-end phones. Though it maybe unexpected, entry-level mobiles these days do have the processing power and display screen appropriate for emulating a graphing calculator. Take for example a HP 49g+ graphing calculator with a resolution of 131 x 80 pixels, and contrast it with an entry-level Sony Ericsson J300i with a resolution of 128 x 128 pixels. Mid-range cell phones offer even higher resolutions of 176 x 220 pixels (that’s over 3.5 times more pixels than the HP 49g+).

Cost-wise, the commonly recommended graphing calculator for educational purposes is the US$100+ TI-83 Plus, US$130+ TI-84 Plus and the US$150+ HP 49g+. In comparison, an entry-level Sony Ericsson J300i retails for US$75+, or free with a 2-year service agreement.

The TVH-72g Graphing Calculator

Created by Tea Vui Huang, the TVH-72g Graphing Calculator is a small 14 Kbytes Mobile Java program that can be installed over-the-air (OTA) or locally via infra-red or data cable from a PC or notebook. For the latter, the student's phone may be equipped with the software using a school computer hosting a copy of the license-free TVH-72g Graphing Calculator. The TVH-72g occupies barely 0.1% of the J300i's 12 Mbyte phone memory; it can also be easily deleted by the student when it's no longer needed.

The keys on mobile phones are generally not arranged in QWERTY format, which fits one of the requirements for using graphing calculators in exams. The TVH-72g has no memory functions and does not use the exam-forbidden Computer Algebra System (CAS). The TVH-72g graphing calculator plots graphs of quadratic equations and trigonometric functions.

Quotable quote

An introductory graphing calculator for mobile phones has been built (the TVH-72g Graphing Calculator) and has shown that the OGCPS is technically feasible.

Links

• Tea Vui Huang's TVH-72g Graphing Calculator for mobile phones (screenshots & software download)