Hands-on Activity: Decimals, Fractions & Percentages
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Students should already have be introduced to the concepts of decimals, fractions and percentages, and be able to multiply and divide decimals.
In order to conduct this activity, it helps if the teacher is familiar with building and operating the LEGO MINDSTORMS NXT kit and programming the robot with the NXT software, although the necessary program is provided.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
Note that single licenses and site licenses are available; site licenses may make sense for schools with high use.
Introduction/Motivation (Return to Contents)
Throughout the course of our lives, many situations will arise in which we will be faced with using decimals, fractions and percentages. Gaining a complete understanding of what they are and knowing how to convert between these number forms is imperative.
Where might we use decimals, fractions and percentages? (Listen to student ideas and examples.) Well, of course we use them in our school classes, such as math and physics, but in most other classes, too (such as "percent of the planet's surface covered in oceans" or "8 of the 12 beans sprouted" or "ratio of basketball game wins to losses"), and even grading! We'll use them in our future jobs and careers, almost all of them, including engineering (such as: representing the safety factor for a structural part by a fraction or a decimal, or indicating the probability of a certain risk, ranging from 0 to 1, in decimal or percentage forms). And in we use them in our everyday lives, such as leaving a tip at a restaurant, or making salad dressing using a specific ratio of oil to vinegar.
When shopping, have you ever noticed signs such as "50% off" or "half off"? To double-check the price of something, or to compare prices, we often do quick calculations in our heads that require us to convert percentages or fractions to decimals to more easily work it out. A number such as 50% may be easy to understand, but if something costs 120% more, it might be easier to convert this number to a decimal to do the math. When tax is added to the purchase price, say 8.875%, we commonly convert this percentage into its decimal format to make it easier to do a quick calculation.
These and many more examples show the advantages to being able to convert easily between the decimals, fractions and percentages in everyday life.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
The LEGO MINDSTORMS NXT robot is an ideal tool for teaching students math and science concepts. By having fun while learning new concepts, students remember what they are taught. This is the primary motivation behind the use of NXT robots in the classroom.
The LEGO NXT robot used in this activity is a simple "five-minute bot" with a touch sensor added. The touch sensor serves as an interface to enable students to enter any fraction of their choosing. The first use of the touch sensor selects the numerator; the next use of the button selects the denominator; pressing the enter button on the NXT brick stores each number. Then students convert this fraction, by hand calculations, into a decimal and then a percentage. As they proceed, they use the robot to double check their work. Next, the robot moves a distance, based on the input fraction, so students must apply their prior knowledge about multiplying and dividing decimals to calculate the full distance that the robot is moving. This works well as a game. Groups each select a fraction, which in turn instructs the robot to move that fraction of the unknown full distance, with the goal being to determine the correct fraction to move the robot a target distance. The group that gets the robot the closest to a target wins.
Before the Activity
With the Students
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
Make sure all motors and sensors are correctly connected to the ports specified in the program.
Assessment (Return to Contents)
Pre-Activity Quiz: Before beginning the activity, administer the DFP Pre-Activity Quiz to determine how familiar students are with the topic of converting between decimals, fractions and percentages. This assessment also alerts students to what they will be learning.
Worksheet: During the DFP Presentation, have students use the DFP Worksheet to practice solving conversion problems. The worksheet provides the same type of problems as the pre-quiz and post-quiz. Review students' work and answers to assess how much they learned from the presentation. In addition, ask students be come up to the classroom board to solve examples from the worksheet and presentation.
Post-Activity Quiz: At activity end, administer the DFP Post-Activity Quiz to determine how much students have learned from the activity. Questions are similar to the pre-activity quiz and worksheet.
Activity Extensions (Return to Contents)
For additional explanation and practice problems, direct students to the video and problems at the Kahn Academy, as described in the last slide of the presentation and listed in the Additional Multimedia Support section.
Expand the activity by teaching students about fractions greater than 1. For example, based on a robot with a target distance of 10 feet, a robot input fraction of 15/10 would move the robot a distance of 15 feet.
Additional Multimedia Support (Return to Contents)
Five-Minute Bot building instructions: http://www.nxtprograms.com/five_minute_bot/steps.html
LEGO NXT touch sensor information: http://mindstorms.lego.com/en-us/products/default.aspx#9843
Khan Academy video instruction and practice problems on "Representing a number as a decimal, percent and fraction" (5:25 minute video): https://www.khanacademy.org/math/arithmetic/decimals/percent_tutorial/v/representing-a-number-as-a-decimal--percent--and-fraction-2
Supporting Program (Return to Contents)Applying Mechatronics to Promote Science (AMPS) GK-12 Program, Polytechnic Institute of New York University
Acknowledgements (Return to Contents)
This activity was developed by the Applying Mechatronics to Promote Science (AMPS) Program funded by National Science Foundation GK-12 grant no. 0741714. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.