GRADE: Third

CONTENT STANDARD: Physical Science

CONTENT TOPIC: Simple Machines/Technology

CONCEPT: Machines use energy to make work easier.

CONTENT OBJECTIVE: 3A1.00 To understand the scientific meaning of work

INSTRUCTIONAL OBJECTIVES: The learner will:

1.01 define work as the movement of an object through a distance.
1.02 define gravity and identify work caused by gravity.
1.03 measure the distance an object is moved by a force.

I. Define and discuss work
II. Define and discuss gravity
III. Discuss how an object is moved by force

TN COMPONENT OF SCIENCE: Process Of Science

TN GOAL:

To enable students to demonstrate the process of science by posing questions and investigating phenomena through language, methods and instruments of science

1.2 QUESTIONING - The development of an inquisitive mind and the effective use of questioning techniques furthers the acquisition of information.

The learner will understand that:

1.2b Questions may be structured so that they can be investigated scientifically.

BENCHMARK: The formulation of questions which address a specific concern or problem more readily lend themselves to scientific investigation.

TIME REQUIRED:

One instructional period

One unbreakable object, pendulum made of thread, ruler, paper clips, tape, different sized weights, force-o-meter, rubber bands

Today class, we will define work as the movement of an object through a distance, define gravity and identify work caused by gravity. We will also measure the distance an object is moved by a force.

Work is done when the force applied to an object actually causes it to move. Therefore, work is the amount of force applied multiplied by the distance an object is moved. We call the unit of measurement for work a Newton-Meter.

Gravity is the force of one object pulling on another object. Isaac Newton began to take interest in gravity when he saw an apple fall from a tree. He concluded that the force that causes apples to fall must also be the pull on all bodies in the earth's sphere toward the earth's center.

Newton also studied force. Force is anything that causes a change in motion. Newton realized that the force applied must be greater than the resistance of an object to cause movement. To measure the distance caused by a force we use meters.

(The teacher will drop an unbreakable object. Ask ALL children to describe the direction in which it falls. Explain that the direction should be described as "toward the earth" instead of "down.") Work is done when a force moves something. (Demonstrate pushes and pulls of various objects. The teacher will identify the force and distance involved.)

Gravity is a force which acts upon objects and systems. A pendulum is a system which can be used as a timing device such as in a clock. We can use it to investigate the relationship of forces acting upon objects in motion.

Plans to construct a pendulum:

1. Cut lengths of string. Suggested lengths are 6,12,24 (or x, 2x, .5x) attach washer or other weight to one end of sting. Attach other end to yard stick or stationary object (table top, etc.)

2. Collect data on the number of swings a pendulum makes in 10 seconds.


a. Make a pendulum with one string (length x)
b. Predict the number of swings the pendulum will make in 10 seconds.
c. Measure and record the number of swings that are made. Repeat this process twice.
d. Construct pendulum with length 2x.
e. Predict the number of swings that are made. Repeat this process twice.
f. Measure and record the number of swings that are made. Repeat this process twice.
g. Repeat steps D, E, F for a pendulum with the length .5x.
h. Predict the number of swings for a pendulum with a length of 3x and record.

3. Create the graph. Using the 2x pendulum as a standard mark on the string (with masking tape) the other lengths used (x and .5x). Hang this string on the hanging graph on the wall. Use the numbers of swings by the 2x pendulum as the x-axis value.

4. Discuss activity results


a. As a group, review the data collected during the activity. Record any specific comments or findings.
b. As a group, examine and interpret the "Hanging Graph" on the wall.)

1. Have students use the letters in the term GRAVITY to name objects that are pulled toward the earth by gravity. Each object should begin with a different letter.

2. Introduce the vocabulary word, GRAVITY. Students can make a pendulum with thread, ruler, paper clips, and tape. Have the students experiment with a length of thread and a number of weights to see what affects speed of swing and what pulls the weight down. Before doing the experiment, have the students predict how the length of the pendulum will affect the swing speed and how the amount of weight will affect the swing speed.)

Think of a chore that you are responsible for doing at your house. We will take turns acting out the job. The rest of the class will try to guess your job. Everyone will get a turn. (To save time, you could work in groups.)

Today, class, we have defined work as the movement of an object through a distance, defined gravity and identified work caused by gravity. We have measured the distance an object is moved by a force.

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