### Purpose

To know the six simple machines and to understand what they do and how they have changed the lives of humans.

### Context

In grades K-2, students learn to use certain simple tools such as rulers or magnifiers. They come to understand that these tools help them do things, like measure and see close up, so they are familiar with the basic thought that tools help humans accomplish tasks more easily. (*Benchmarks for Science Literacy*, p. 10.) This lesson expands on that thought by introducing students to and leading them in an exploration of the six simple machines.

This is the grade level where students start to examine tools and machines, and how they improve the lives of humans. (*Benchmarks for Science Literacy*, p.127.) Therefore, students may or may not be familiar with the six simple machines: lever, wedge, pulley, wheel and axle, inclined plane, and screw. An understanding of the simple machines provides a platform for students to understand the basis of complex machines and systems.

Even if students already know of them, the discussions and activities in this lesson will add to what they know. At the same time, we encourage you to use this lesson in conjunction with other materials. If your students are in third or fourth grade, you may want to use the lesson in full as a solid introduction to other explorations of simple machines. If your students are in the fifth grade, and know the basics, you may want to skip right to part two of the development and supplement that and the assessment with other resources.

Students will start by discussing a couple of the simple machines and what the purpose of them might be. Then, after reading a short page on each simple machine, they will discuss how the simple machines function. They will explore this briefly in a hands-on fashion and lead into the discussion and realization that these tools are the base for almost any machine or more complex tool that we use. There will also be some acknowledgment of how tools make our lives easier.

This lesson can be used either before or after Tools. While Tools explores the functions of complex machines and how they have made our lives easier, it does not specifically discuss and name simple machines.

### Motivation

Put a box filled with books on your desk or on the floor at the front of the class. Ask a couple of students to come up and try to nudge the box. You don’t want them to try to actually lift it because it will be heavy and they could hurt themselves. You just want to prove that the box is fairly heavy. Ask the class:

- You could probably lift this box, but not easily. What if you had to put it on a shelf that was as high as the ceiling? How would you get it up there?

(Write this and all of the following answers on the board. You are not quite ready to introduce the simple machines so use whatever language your students use. You will revisit these ideas somewhat immediately.) - What if you had to carry the box home?

(If students do not get beyond just carrying the box and taking rests, add to the question and ask: Are there any devices that could help you? It may be that students are coming up with “things” that incorporate one of the simple machines, like a cart or a dolly. If so, this is a great lead in to the lesson.)

### Development

**Part I Introduction to Simple Machines**

Have students read Dirtmeister’s Science Reporters: Simple Machines. They will start on the second page, which describes the inclined plane. At the top of the page is a list of the other five simple machines. Instruct them to read about each one. These readings are fairly short. When they are finished, go back to the box. Ask students:

- Do you have any new ideas about how you would put the box up on a very high shelf?

(Students have just read about the pulley, which is a pretty obvious answer. Write pulley on the board after students have offered up the answer. Lever is a possible answer, though maybe not the best choice for the task.) - What about carrying the box home? Is there a machine that could help you?

(After students answer, put wheel and axle on the board.) - Are there other ways to move the box, if you simply had to move it?

(You could slide the box down an inclined plane, or lift it with a lever.) - What do the simple machines we’ve discussed so far do?

(Simply, the machines help us move things.) - Which simple machines are not up on the board?

(The screw and the wedge.) - What are these machines good for?

(Both are also used to move things in the simplest sense, however the screw seems to have more of a function of holding things together.)

**Part II Students Make Simple Machine Stations**

In this part of the lesson, students will create simple machine stations. They will quickly assemble a simple machine and then make a group poster to show what their station represents.

Break students into six groups. Give each student his or her own Your Simple Machine Station student sheet. While they are reading the instructions, put out the materials that they will need for the basics of their station, including poster paper and construction paper, glue, etc.

Put out the following for the student groups:

- For the lever: a board, something to balance it on (a stack of books is suggested) and something to lift with it (a small box filled with something to make it heavy is suggested)
- For the inclined plane: a board and a small box filled with something to make it heavy
- For the wedge: a stack of books and a wedge of wood
- For the pulley: a rope, an empty spool with a pencil that fits through the middle and something to lift. (Note: You may need to assist students. For instance, two students will need to hold either side of the pencil or they will need to balance the pencil across two stacks of books or across the space between two desks. They will also need to wrap the rope around the spool twice and leave enough on one end to pull and enough on the other end to tie up something.)
- For the screw: a piece of wood and a few screws, a screw driver

**Optional:** The wheel and axle is optional depending on supplies and the students you have. In order to fully demonstrate the wheel and axle, the item to be moved must somehow attach to the axle. This could require an assembly much more complicated than that listed above. A spool of thread could serve as the wheel, a pencil for the axle, and you could challenge students to build a “holder” that attaches to the axle.

It shouldn't take long to assemble the machines. Students may need time outside of class, however, to finish their posters.

Once they are done creating their stations, ask these questions:

- Do you think different simple machines have different uses?

(Yes and no. While all simple machines move things, the screw for instance has quite a different purpose than say the pulley. Try to get students to create different scenarios using different machines.) - Did anything about your simple machine surprise you?

(This offers an opportunity for students to share any discoveries they made. Some students may have been surprised at how much their simple machine helped to move something.)

### Assessment

Since the main benchmark idea is that tools and machines help humans "sense and do things that they could not otherwise sense or do at all, or as quickly, or as well," you will want to make sure that students understood this through the development.

Pass out lined paper to your students and instruct students to do the "Observations" part of their student sheets, which will instruct them to observe one of the simple machines from a station that is not their own. They will turn in a write-up about their observations that should demonstrate that they understand the difference between doing a task with versus without the help of a simple machine. The write-up should also demonstrate that students understand the benefit of the simple machine described.

### Extensions

This lesson can be used either before or after the Tools lesson that explores the functions of complex machines.

Dirtmeister's Science Reporters is used as a reading source for this lesson. Using the rest of this site for an add-on would work well. The Observe and Record and the Report Your Findings give students worksheets that instruct them to go out and observe machines, then to identify the simple machines they see. Dirtmeister's site has some emphasis on the tradeoffs of simple machines, something that is not covered in this lesson.