Description:

Students are to construct pendulums and experiment with what variables change or effect the rate at which they swing through an arc.

The task assesses students' understanding of scientific inquiry including the following skills: observation, data collection, measurement, graphing, scientific questions.

This task is designed to take students approximately 2 hours.

Overall Task Content Area:

Physical Science

Specific Knowledge Areas:

Position and motion of objects

Performance Expectations:

• conducting investigations
• using equipment
• gathering, organizing, and representing data
• formulating conclusions from investigational data

National Science Education Standards:

8 A SI 1: Abilities necessary to do scientific inquiry: Grades 5-8
1.2 Design and conduct a scientific investigation. Students should develop general abilities, such as systematic observation, making accurate measurements, and identifying and controlling variables. They should also develop the ability to clarify their ideas that are influencing and guiding the inquiry, and to understand how those ideas compare with current scientific knowledge. Students can learn to formulate questions, design investigations, execute investigations, interpret data, use evidence to generate explanations, propose alternative explanations, and critique explanations and procedures.

1.4 Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description — providing causes for effects and establishing relationships based on evidence and logical argument. This standards requires a subject knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.

1.7 Communicate scientific procedures and explanations. With practice, students should become competent at communicating experimental methods, following instructions, describing observations, summarizing the results of other groups, and telling other students about investigations and explanations.

1.8 Use mathematics in all aspects of scientific inquiry. Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions; to gather, organize, and present data; and to structure convincing explanations.

8 B PS 2: Motions and forces: Grades 5-8
2.3 If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object’s motion.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

General Instructions to the Teacher:

This task is designed to take students Approximately 2 hours

Students will be working individually during this exercise.

Students should be ready to work as soon as periods begin. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for "Pendulum":

The teacher will need:

• string
• tape
• meter stick
• weights, washers or pennies on paper clips
• clock with a second hand
• protractor

Advance Preparation:

• Demonstrate for the class the procedure to measure the time (in seconds) for one complete cycle of pendulum (one cycle is the time it takes to return to the starting point).
• Brainstorm variables that could change that time including: mass, angle from which it is released, length of string, combinations of the above. It is easiest if the students start with pendulums that are about 50 cm long. These can be hung from pencils taped to their desks.

Safety:

• Be careful.
• Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.

Extensions/modifications:

• N/A