Digging for Gold! Teacher Science Activity

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Activity Title: 'A Special kind of Lever'

Subject Area: Science

Grade Levels: 5th + 6th

Students will investigate the use of machinery in the early days of mining. They will construct a simple pulley, then observe that a pulley reverses the direction of applied force. Students will discover how pulley systems allowed for the movement of heavy mining equipment to the gold fields.

Colorado Standard(s) and/or Benchmark(s) addressed in this activity:

*Grade*	*Content Area*	*Standard*	*Benchmark*
5^th + 6^th	Science	1 - Scientific Investigation	1.1 Scientific investigation
5^th + 6^th	Science	2 - Physical science	2.2 Forms of energy
5^th + 6^th	Science	2 - Physical science	2.3 Interactions of objects within a system
5^th + 6^th	Science	5 - Science, Tech, H.A.	5.1 Science, technology and human activity
5^th + 6^th	Science	6 - Scientific connections	6.1 Scientific connections

National Standard(s) and/or Benchmark(s) addressed in this activity:

*Grade*	*Content Area*	*Standard*	*Benchmark*
5^th + 6^th	Science	A - Scientific Investigation	A.1 Scientific inquiry
5^th + 6^th	Science	B - Physical science	B.2 Motions and forces
5^th + 6^th	Science	B - Physical science	B.3 Transfer of energy
5^th + 6^th	Science	E - Science, Tech, H.A.	E.2 Understanding about science and technology
5^th + 6^th	Science	G - Scientific connections	G.1 Science as a human endeavor

School to Career Skills:

Academic Skills (science, math, technology)
* Students will read and interpret information
* Students will utilize computation and measurement skills.

Communication skills (oral presentations, written communication)
* Students will use oral presentation skills to communicate scientific discoveries about pulleys.
* Students will use written communication to draw, label and record observations about pulleys.

Technology skills
* Students will access information electronically to use in written research.

Thinking skills (creative thinking, decision making, problem solving, reasoning)

Vocabulary:

pulley
mechanical advantage

Materials:

journal to record data
fishing line
book
scissors
meterstick
string
pulley
spring scale

Preparation: Cut one 30cm length of string, one 60cm length of string, one 1.5 m length of fishing line. If groups of students are completing the activity, each group will need the above materials.

Procedure:

Students will select a book (mass of about 2 kg to provide substantial resistance) to lift using the pulley. They will measure the distance from the floor to the top of a desk. Tie the 60 cm length of string around the book (see fig. 2 a).
Have a student insert the 30cm piece of string through the center of the pulley and hold the pulley above the desktop by the ends of the string.
Another student will tie the 1.5 m of fishing line to the string around the book, loop the fishing line over and into the groove on the pulley (the pulley has become fixed as it is held in place), then attach the spring scale to the other end of the line.
A student will pull DOWN on the spring scale to lift the book from the floor to the desktop. Students will record the force in newtons used to lift the book and the distance that the book was lifted. (Work=Force x distance)

5. Rearrange the pulley system so that one end of the 1.5 m fishing line is tied to the desktop, the pulley is tied to the top of the book, the fishing line is threaded through the pulley and attached to the spring scale (see figure 2 b). A student will pull UP on the spring scale to lift the book to the desktop. Record the reading on the scale. (The pulley has become a single movable pulley in this arrangement)

Analyze and Conclude:

When you use a fixed pulley, what direction did you pull on the string? In what direction did the book move?
Compare the weight of the object with the force used to lift the object with a fixed pulley.
Compare the weight of the object with the force used to lift it with a movable pulley.
How did each pulley arrangement help you do work on the object?

Assessing Student Performance:

Did students measure and record data accurately? Could they interpret data to make inferences about the usefulness of a pulley system?
Can students develop an operational definition of a pulley? Do they understand that a movable pulley provides a mechanical advantage while a fixed pulley does not?
Did students determine from their data that a fixed pulley would change the direction of force, while a movable pulley reduces the amount of effort required?

Assessment Rubric:

Advanced proficient 4	Proficient 3	Partially proficient 2	Unsatisfactory 1
Students accurately measure materials to test a pulley system with a spring scale.	Students accurately measure materials; gather appropriate materials to test a pulley system.	Students measure materials needed; list of materials incomplete to conduct the experiment.	Students do not demonstate skills to measure accurately nor gather materials appropriate for the experiment.
Students demonstrate the ability to test a spring scale and pulley system in a variety of ways, testing various objects.	Students demonstrate the ability to test a spring scale and pulley system according to dircetions.	Students assemble the pulley system, however, are unable to accurately measure the object.	Students are unclear as to how to set up the lever system with a spring scale, pulley, and object.
Students accurately record data in their journals, listing their findings and predicting what will happen. Writing reflects inferences about the usefulness of pulley systems	Students accurately record data in their journals, listing their findings and predicting what will happen in clear, concise writing.	Student list of recorded data is partiallycomplete; lacks details to make a valid inference about the experiment.	Student data recorded in their journal does not reflect an understanding of logical outcomes.
Students accurately list (5) uses of pulley systems in the school environment. They create/demonstrate a pulley system that would model those in use in the Palmer River gold fields..	Students accurately list (4) uses of pulley systems at school. They create and demonstratea simple machine model that would help miners retrieve gold ore.	Students identify (3) pulley systems in use at school. They create a model of a simple machine at work.	Students cannot identify a pulley system.

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