Ratio Challenge

Description

In the Right Ratio of Rest, students use proportional reasoning to determine the amount of sleep people need in light-dark cycles that are different from the one on Earth.

A ratio is a comparison of two numbers by division. Ratios are used in many real-life situations. In the physical world, gears are used to change the direction and speed of the applied force. Gears often work in pairs. They come in many sizes and shapes. Gears can be compared by the ratio of the number of teeth.

The interactive Squeak web activity is designed to help students understand ratios. They will be able to bring gears of different sizes with different numbers of teeth into the gear test area and make measurements. They will count the number of teeth in each gear and from the ratio of the number of teeth predict which gear will turn faster. Then they will measure the ratio of turns of the smaller to the larger gear and compare the ratio of turns to the ratio of teeth. They will take more data to explore the relationship between the two ratios. There are four possible gears to choose from so students will be challenged to determine how many different combinations of two and three gears there are. The Squeak activity doesn’t quite work right for three gears and more advanced students are challenged to fix the activity so it works for three gears.

This activity uses a free, exciting, multimedia, object-oriented programming environment called Squeak that runs on many different computer platforms. Important Note: This activity uses the new version of Squeak made available in September 2004. If you installed Squeak prior to that, you should update your version of Squeak at www.squeakland.org.

If you don't have Squeak installed on your computer, you will need to first download the plug-in for Squeak before doing this activity. You can download the plugin for Squeak at www.squeakland.org and then double-click the downloaded icon for easy installation. Once you have the Squeak plugin installed, you can click on the image above or link below to start the activity. You can also get a valuable Squeak Quickstart guide and other information at the Squeakland web site to help when doing this project. Once you have the Squeak plugin installed, you can click on the image above or link below to start the activity. Set your resolution to 1024x768 to use this Squeak project.

Instructional Objectives

The student will

• measure and record data on gears.
• calculate ratios.
• compare the ratios they determine and look for a pattern in their measurements.
• find the number of combinations of two and three gears if you have four gears to choose from.

Go to Squeak Ratio Challenge Web Activity