Project overview 

In this guided lesson the main goal is to show the student the applications of the four-bar mechanism and involve them through the construction of a four-bar mechanism using simple materials.

Age group

This lesson is intended for 10 - 12-year-old students. 

Duration 

50 - 60 minutes 

Vocabulary 

- Mechanism
- Linkage 
- Link
- Crank 
- Rocker
- Inversion 
- Grashof law 

Goals 

- Understand how the four-bar mechanism works and its usage.
- Understand the different types of four-bar mechanisms and the relationship between inversion and length of links.
- Create a four-bar mechanism using common materials. 

Materials

- Thumbtacks.
-  Icecream Sticks. 
- Scissors.
- Ruler.

Resources 

- Crank Rocker Mechanism - https://www.youtube.com/watch?v=fCcWGXL-2Z8
- Design of Machinery: An Introduction to the Synthesis and Analysis of Mechanisms and Machines 3rd Edición - https://www.amazon.com/-/es/Robert-L-Norton/dp/0072864478

Lesson 

Part 1 ( 25 minutes)

In this part of the lesson the students will learn about the four-bar mechanism, thy will learn the application of the crank-rocker mechanism in machines such as fans and wiper washers, additionally, they will understand the Grashof law and how to use it in order to make the linkages the right size for achieving the required movement. 

Part 2 ( 30 minutes) 

For this part of the lesson, the students have to use the Grashof law in order to choose the sizes of the linkages to make a crank-rocker mechanism, later they will measure, cut, assemble and decorate, their own mechanism in groups.

Part 3 ( 10 minutes) 

Every team has to make a presentation of the mechanism in front of the class.