Students use simple machines to examine the relationships between force and motion, complete a science journal, and participate in group activities to demonstrate the use of simple machines. Grades 3-5

agriculture: the science or practice of farming, including cultivation of the soil for the growing of crops and the rearing of animals to provide food, wool, and other products

energy: power derived from the utilization of physical or chemical resources

force : a push or a pull on an object

friction: a resistant force caused by rubbing

fulcrum: a pivot point on which a lever turns

lubricant: a substance such as oil or grease applied to an area to make objects move with less friction

movement: an action or activity

work: a force applied over distance causing the movement or displacement of an object

This lesson is part of a series called, Simple and Complex Machines Used in Agriculture. These lessons introduce students to the simple and complex machines used in their daily lives and in food and fiber production. Through a variety of hands-on activities, students create models of the six types of simple machines and discover the concepts of force and friction. The essential role of complex machines in people's daily lives and in agriculture is interwoven through a number of class and homework activities that incorporate cooperative learning, writing, mathematics, art, and drama. Together these activities are designed to stimulate creative thinking and motivate learning. Other related lessons include:

• Machines and People
• Six Kinds Do It All
• Made to Move
• Machines in Agriculture

Prior to this lesson students should have a basic knowledge of the six simple machines. Machines involve the force of a push or pull. Machines cannot create energy; they use the energy available in an efficient way. Stored (potential) energy is converted to mechanical (kinetic) energy.

As energy is transformed from one form to another or transferred from one object to the next, some of it is converted into heat energy because of friction. Friction is the force between two surfaces that resists the motion of one object past another. Friction is useful when one does not want an object to slip. Friction is important when a tire rolls across a road, or sandpaper rubs across wood. Other times friction is less desirable. For example, the rubbing between metal in machine parts causes them to wear down or release heat in unwanted areas. The use of lubricants and ball bearings can reduce unwanted friction. Machine lubricants come from many sources, including fossil fuels and inedible beef fats.

The station activities in this lesson allow your students to experience firsthand the six simple machines in action and the effect friction has on the efficiency of the machines. The students will also observe the effects of lubricants and ball bearings.

1. Prior to this lesson, your students should have a basic knowledge of simple machines. Show your students the three farm pictures. They can be printed or projected on a screen. Each picture contains a scenario on the farm where a simple machine can be used to complete a task.
2. Allow students to use their knowledge to try to determine what kind of simple machine will help perform the work. There can be more than one correct answer. Use the pictures to stimulate discussion and interest. Although complex machines can be used, keep the discussion focused on simple machines.
   • Moving the baby calf: Placing the calf in a wheel barrow uses both a wheel and axle and a lever to lift the weight of the calf and move it to the new location.
   • Transporting grain to the silo: Grain is often moved from place to place with an auger. An auger is a rotating screw located inside a tube. As the screw rotates, the grain is moved up the tube and into the silo.
   • Transporting hay bales: Most large hay bales are lifted using a loader. Loaders use a lever to lift the bale. The bales are then loaded onto a trailer which uses wheels and axles. 

1. Divide students into eight groups. Distribute the Science Journals to the students. The journals should include the title page and all of the station worksheets stapled together. It may also include blank pages for writing assignments prompted by you or your students.
2. Place the station materials in eight locations around the room.
3. Have the groups rotate from station to station every 15-20 minutes. Four rotations might be done one day and the rest another day. Set up the format to accommodate what works best for your classroom.
4. Have the students complete each activity and worksheet at the appropriate station. Each worksheet contains directions for a self-directed activity. Some guidelines for successful station work are described below:
   1. Preview the experiments with the students before they begin the station activities.
   2. Review your classroom expectations on cooperation, set-up, participation, and clean-up.
   3. Assign roles to each member in the group such as supply person and time monitor.
   4. Inform your students of the time five minutes before changing stations.
5. When the rotations are complete, direct a discussion about what the students discovered. Ask them to share their science journal writings with one another.

Variations

• Do each station as a whole class activity.
• Assign older students from another class to be the leaders for each station.

After conducting these activities, review and summarize the following key points:

• There are many simple tools and complex modern machines used in agriculture.
• Tools and machines make the process of growing and producing our food and fiber easier and more efficient.
• Farmers and ranchers can produce more food with less effort with the use of machines and tools.

This lesson was funded in 1996 by the California Beef Council and the California Farm Bureau Federation. To meet the needs of California educators, Simple and Complex Machines Used in Agriculture was revised to support the Curriculum Content Standards for California Public Schools and updated to include recent agricultural innovations. Funding from the Wells Fargo Foundation made this revision possible.

Illustrators: Karin Bakotich, Pat Houk, Sherri Hughes, Regina Johnson

Layout and Design: Nina Danner

• Big Book of Big Tractors
• Big Tractor
• Hey, Hey, Hay!
• Machines on the Farm
• Simple Machines: Wheels, Levers, and Pulleys
• Tractor Timeline- A History of Tractors
• Trax the Tractor and His Farming Friends
• Up Close Experience: Combines