A Complex Solution

Students design a machine, using two or more simple machines, to solve a specific problem. They draw the machine and describe how it functions. If possible, student groups construct a model of their machine and demonstrate how it works in the classroom.

• 1 lever (ruler, fulcrum)
• 1 gear set
• 1 pulley
• plastic drinking straws
• tape
• student assessment sheet

Leading the Activity

Encourage student groups to brainstorm and discuss a problem to solve, and how they can design a complex machine as a solution. Guide students to focus on a simple problem that can be solved. Point out that they will be using some of the materials that they have worked with throughout the module. Review the procedures with the students.

Procedure

1. Brainstorm a list of problems that you would like to solve.
2. Select and discuss one problem.
3. Design a machine that can solve the problem.
4. Draw your machine and label the simple machines that are included.
5. Indicate, with arrows, each place where a force is applied in the machine.
6. Write a step by step description of how the machine works.
7. Construct your machine, if possible, and demonstrate how it works.

Range of Results

Students may find it challenging to think about a simple problem that can be solved with the invention of a complex machine. Continue to guide their thinking by asking questions. Some exam-ples of guiding questions might be: What do you find hard to do that perhaps your machine might make easier to do? How could you use your machine to help you do something in the classroom, or at home? What job do you have at home that might be made easier with your machine? How can you design a machine that might help you take care of a pet?

In assessing student groups, take into consideration:

• how they combined the simple machines to design the complex machine;
• where the arrows are placed to indicate the application of force; and
• the step by step description of how the machine works to solve the designated problem.