Overview and Background

Every year after completing a science unit on how electric motors work, the class takes what they have learned and creates a small car using cardboard, straws and bottle caps. They add a motor and a rubber band to power the car. The project culminates with a car race in the gym. The best design is the one that gets to the finish line (half-court) first. Previously all students used bottle caps for their wheels. This caused cars to not drive straight or very fast. This year students were given the option of designing parts to be printed on the 3D printer.

Lesson Plan and Activity

Lesson on Electric Motors

Attached is a lesson from IEEE on how electric motors work and how to build one. This is the first step in the car building process.

https://www.ieee.org/contrib/groups/public/@ieee/@web/@org/@educ/documents/file/20041417.pdf

Building the Car

Taken from: http://www.miniscience.com/kits/CAR_ELEC/

Electric Car

Introduction:
Making an electric car is a mechanical engineering challenge often used as a competition for students from 5th grade up.

An electric car is driven by a DC electric motor, powered by one or two batteries.

Transmission of force from the motor to the car axle is accomplished using two pulleys and one rubber band acting as a belt. A simple switch made of a paper clip is used to connect or disconnect the circuit. Wheels are made of larger pulleys with rubber rings as tires. The car chassis is made of cardboard, reinforced by drinking straws.

For our cars, students designed the wheels and the pulleys using tinkercad.com. They needed to decide how big they wanted each to be. They needed to take into account the inertia that needed to be overcome, and the weight the motor must move.

With this project students can explore:

A simple propulsion method
Basic gluing techniques and design concepts
Concept of stored chemical energy energy and converting it to mechanical energy
A simple electric circuit

During construction of the electric vehicle, students can experiment and comprehend methods of power transfer, using glue, measurement, making a simple electric circuit . It is up to the teacher to make sure this background information is provided to students in some manner.

Background

Before invention of gas engines, cars were pulled by horses or other animals. Now gas burning engines are the most popular drive in cars. There are concerns about the air pollutions caused by gas engines and electric cars are entering the market in a fast pace. Electric cars rely the electrical energy stored in batteries, so they will not cause any air pollution.

Because of the limited amount of electricity stored in batteries, electric cars must be made very light so they can transfer a longer distance with a limited amount of energy.

Assembly Procedure

1.Before students construct their vehicles, they will make a complete blueprint of their design to scale..They must get approval of their design before they begin building.

After the design is approved, a list of needed materials is made, and the designs requiring 3D printing are submitted to be printed. For this iteration, students designed wheels and pulleys. For the next time this project is completed, students will also design a frame for their cars to increase the stability.

Construction of an electric car is an engineering/ technology project. When you try your car in a race, the one that is built with more precision and more considerations, will be the fastest. To build and use this car as a science project, you may find a research subject that is closely related to that. For example you may try to find out:
Which battery brand provides the most power to your car?
What effect does wheel size have on the car's performance?
What size combination for pulleys gives the best performance? (small to large?, Large to small? or same size?)
What works better - the pulley system or gear system?

Materials Needed

Cars are to be made out found materials: cardboard, straws, wooden dowels (skewers), glue guns, 3D printed parts (Wheels, pulleys, frames?)

Standards

National Science Education Standards Grades 5-8 (ages 10 - 14)
CONTENT STANDARD B: Physical Science
As a result of their activities, all students should develop an understanding of
Motions and forces
Transfer of energy
CONTENT STANDARD F: Science in Personal and Social Perspectives
As a result of activities, all students should develop understanding of
Risks and benefits
Science and technology in society
CONTENT STANDARD G: History and Nature of Science
As a result of activities, all students should develop understanding of
History of science
National Science Education Standards Grades 9-12 (ages 14 - 18)
CONTENT STANDARD B: Physical Science
As a result of their activities, all students should develop understanding of
Motions and forces
Interactions of energy and matter
CONTENT STANDARD E: Science and Technology
As a result of activities, all students should develop
Abilities of technological design
Understandings about science and technology
CONTENT STANDARD G: History and Nature of Science
As a result of activities, all students should develop understanding of
Historical perspectives
Standards for Technological Literacy - All Ages
Technology and Society
Standard 7: Students will develop an understanding of the influence of
technology on history.
Design
Standard 10: Students will develop an understanding of the role of
troubleshooting, research and development, invention and innovation, and
experimentation in problem solving.
The Designed World
Standard 16: Students will develop an understanding of and be able to select
and use energy and power technologies.

Skills Learned

motor
electric car
engineering
3D design

Duration of Lesson

Depending on what parts are available to students, and how many iterations of designs are allowed, can take up to two weeks of class

Preparation

Teachers could have all the supplies laid out for students, or the students can be made responsible for their own supplies.

Teachers will introduce the electric motor lesson and have students explore how electric motors work.

Students will learn how to design a scale model for their car.

Rubric and Assessment

Students will be graded on their designs and their cars ability to drive the required distance. Students will present their data and conclusions about their designs and performance as a final assessment by creating a PowerPoint describing their design process.

References

https://www.ieee.org/contrib/groups/public/@ieee/@web/@org/@educ/documents/file/20041417.pdf
http://www.miniscience.com/kits/CAR_ELEC/

Motor Car Science Lesson