Description:

Students analyze how the Law of Conservation of Energy applies to the design and use of scissors. Working in groups, students will determine the output work for a standard pair of scissors.

This task is designed to take students approximately 45 minutes to complete.

Overall Task Content Area:

Physical Science

Specific Knowledge Areas:

Conservation of energy

• conducting investigations
• using equipment
• gathering, organizing, and representing data
• formulating conclusions from investigational data
• applying scientific principles to develop explanations and solve new problems

National Science Education Standards:

12 B PS 5: Conservation of energy and increase in disorder: Grades 9-12
1.5 Law of conservation of energy

12 A SI 1: Ability necessary to do scientific inquiry: Grades 9-12
1.3 Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

1.4 Formulate and revise scientific explanations and models using logic and evidence. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.

12 E ST 1: Abilities of technological design
1.5 Communicate the problem, process, and solution. Students should present their results to students, teachers, and others in a variety of ways, such as orally, in writing, and in other forms - including models, diagrams, and demonstrations.

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

National Council of Teachers of Mathematics:

AL1: Understand patterns, relations and functions:
Grades 9-12 n. interpret representations of functions of two variables

AL3: Use mathematical models to represent and understand quantitative relationships:
Grades 9-12 f. draw reasonable conclusions about a situation being modeled

AL4: Analyze change in various contexts:
Grades 9-12 f. approximate and interpret rates of change form graphical and numerical data

DAP1: Formulate questions that can be addressed with data and collect, organize, and display relevant data to answer them:
Grades 9-12 l. understand the meaning of measurement data and categorical data, of univariate and bivariate data, and of the term variable
Grades 9-12 m. understand histograms, parallel box plots, and scatter plots and use them to display data

PS1: Build new mathematical knowledge through problem solving:
Grades 9-12

RP2: Make and investigate mathematical conjectures:
Grades 9-12

REP1: Create and use representations to organize, record, and communicate mathematical ideas:
Grades 9-12

General Instructions to the Teacher:

This task is designed to take students approximately 45-50 minutes to complete.

Students will be working together in groups of 4 (2-5) for the experiment/activity part of this exercise.

Students work together for up to 20 minutes. They are instructed to notify you when finished with the group work, and then to go on to the individual work beginning with question #2. If students are still working together 20 minutes after the testing begins, instruct them to cease their group work and begin individual work. At this point, they may no longer talk. Whether or not they are just beginning their individual work, remind students that they now have about 25 minutes to complete the individual activity.

Students should be ready to work as soon as the period begins. Group assignments should be made in advance. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for A Cut Above the Rest:

At this station students should have:

• 1 diagram showing scissors apparatus
• 1 calculator for each student
• 1 metric ruler (30 cm) for each student
• 1 scissors apparatus
• 1 spring scale (20 N capacity)
• 1 4.9-N weight (Note: a 500g mass has a weight of 4.9 N on Earth.)
• 1 ring stand
• 2 meter sticks
• duct tape
• pencils

Advance Preparation:

See diagram showing scissors apparatus for instruction on how it should be constructed. You will need to use the ring stand, 2 meter sticks, duct tape, and scissors for each apparatus you will construct. The details of construction can vary as long as the finished apparatus allows students to carry out the procedures described in the task.

Note that the markings on the scissors blade should also be done prior to the test period.

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.