A lever is a simple machine.
A lever is a rigid bar that pivots around a point that is used to move an object at a second point by a force applied at a third point.
An experiment can be created to identify variables and their effects on interactions by using if/then thinking.
It is helpful to have a tentative answer, or hypothesis, as we try to answer our question.
As we become more experienced at asking questions and making predictions, we improve our ability to make careful hypotheses from which we design experiments
Curiosity and persistence are needed to solve and understand problems.
I can create a simple machine if I just keep trying and use the material given.
If one plan doesn’t work, I can try another.
I am capable of using science to better understand the world.
Activity overview: The lesson is designed for students to be involved with hands-on experiences. Inquiry activities are approached by employing a simple learning cycle consisting of exploration, invention, and discovery. Working in groups, students will use a long board and a triangular-shaped block and devise as many combinations as they can think possible to move weighted objects. The goal is for students to make a simple machine to help do work. The basic science process skills of observation, communication, prediction, and inference are prerequisites for the integrated skills of identifying variables, forming hypotheses, and experimenting.
Rationale: This lesson is intended to teach students to be careful observers of a simple machine used in a variety of everyday tools and gadgets. Looking into how levers have improved our world and how these machines could be creatively directed can be exciting for the student. This activity will help to direct the student beyond the “simple machine vocabulary,” extending the thinking process while showing simple machines real usefulness.
Background knowledge for teachers:
A lever is a simple machine that helps people do work. In science, work is defined as force acting on an object to move it across a distance. Pushing, pulling, and lifting are common forms of work. The lever is a simple machine made up of a stiff arm or arms that pivot or turn. The point on which a lever turns is called the fulcrum. The load is the force of the thing you are trying to move. There are three types of levers. They are classed by the relative position of the arm, fulcrum, and load.
A first class lever has the fulcrum in the center (A first-class lever is a fulcrum between effort and load.). A playground seesaw is a first class lever. One end lifts an object up just as far as the other end is pushed down.
A second class lever has the load in the center ( second-class lever is a load between the fulcrum and the effort.). A wheelbarrow is a second class lever. The long handles are the arms of the lever, and the fulcrum is the front wheel.
A third class lever has the effort and load on the same side of the fulcrum with the effort in the middle (A third-class lever is an effort between the fulcrum and load.A third-class lever is an effort between the fulcrum and load.). The effort is always more than the load, (a mechanical disadvantage), meaning you always get less force out than you put in. A fishing pole is a third class lever. When the pole is given a tug it pivots around the fulcrum that is your wrist. One end stays still as the other end flips in the air catching the fish (moving the load).
- Resistance- Opposition of some force
- Friction- Resistance to movement
- Work- Force acting on an object to move it across a distance.
- Machine- an object that will do work for us.
A machine has a motor.
A machine does all the work.
-Diagnostic: “What is a machine? What are machines used for?”
-Formative: “Is the machine making your work easier?”
-Summative: “Can you name three points on a lever and their function?”
-Generative: “What other types of simple machines do you have at home that help you do work?”
-Diagnostic: “Is there a way you could find that out?”
-Formative: “If the lever doesn’t work then what will you do?”
-Summative: “How many designs did you try?”
-Generative: “Where else could we use if/then thinking?
-Diagnostic: “What will you do if your first plan is incorrect?
-Formative: “Are you curious? Skeptical? Open to other’s ideas?”
-Summative: “Why did you try several ways to make a machine?”
-Generative: “How does curiosity and persistence pay off?”
Social assessment to build a community of science learners
-Diagnostic: “What will you do if your idea doesn’t work?”
-Formative: “What does your group think they should do to build a simple machine with the board and triangle?”
-Summative: “Was it helpful to hear other students’ ideas work together?”
-Generative: “What other places might you be able to use group discussions or other people’s ideas?”
Self Assessment :
I understand how a lever works.
I can identify levers in my world.
I understand some levers that I use.
I know how to experiment to find answers to questions.
I would keep trying ideas until I am satisfied that I understand.
I am good a learning and solving problems.
For each student: goggles Safety Precautions: Remind students that safety goggles must be worn at all times. Discourage students from sending the load material flying across the room. Warn them of the potential danger to themselves and other students.
For each group: one long piece of board (18”x ¼”), one fulcrum (proportional in size to the long board—for the 18 inch board, triangular pieces cut out of a 2x4 work well), any proportionally sized objects to be used as load, such as blocks or small books
Divide the class into cooperative learning groups of three or four students.
Ask students to describe how they would make a machine to move a stack of books with one board and a triangle piece.
Ask students what they will do if their first idea doesn’t work.
Share their ideas with the class but do not tell what will work of what will not work. Do not give away answers.
Give one board, a triangle, and the books to each group.
Challenge students to make a machine to move the books.
Ask groups to brainstorm several possible ideas and solutions with group members.
Encourage students to draw in their science journal all the methods they try. They need to identify three points on their drawing—the pivot point, the object being moved, and the place where they applied force to get the object to move.
Ask a member from each group to draw their diagrams on the board.
Have students label the three points.
Have them find similarities for machines that moved the books.
Ask the students if there is any advantage to changing the position of the triangle.
Have students write an operational definition for a machine. (An object that will help us do work)
Share with the class the names of the three points labeled in the drawings: the fulcrum, the load, and the effort.
Ask the students what a machine does.
Ask the students if these machines made it easier for them to do the work.
Ask students what the machine they invented allowed them to do.
Ask the class if they know what this machine is called.
Once the concept lever has been invented, ask students if they see any difference in the placement of the fulcrum on the diagrams.
Using the student diagrams, label the three types of levers-first-class, and third-class.
Ask students if they see a difference in the effort and in each diagram.
Ask students if they can see some practical uses for the different placements of the fulcrum.
Ask students which one would be a wheelbarrow, a fishing pole, and finally a seesaw.
Ask the students how they feel about the activity with simple machines.
Take the students on a lever scavenger hunt around the school.
Look for levers in the building (and on the playground).
Allow students to identify the three types of levers