Editor selections by Topic and Unit

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## AP/Calculus-Based Physics:Measurement and the Language of Physics Units

This topic contains a selection of units designed to help you to teach physics. In physics, using precise measurements and standard units is important in comparing physical quantities and understanding basic concepts.

### Frames of Reference (3)

#### Activities:

All motion is relative to a frame of reference. This interactive animation is a great introduction to a topic that is often difficult for students to grasp.  It shows how the motion of a bouncing basketball looks different depending on whether the observer is standing still, walking in the same direction as the player, or walking in the opposite direction. It offers nine scenarios (frames of reference), and students must answer questions from the observer's viewpoint.

Item Type: Interactive Tutorial
Duration: 20-30 minutes

When introducing frames of reference, it helps if your students have a sense of scale. In this wonderful update of "Powers of 10", your students view images of the Milky Way at 10 million light years from Earth, then move through space at successive orders of magnitude until they reach an oak tree in Florida. After that, the applet decreases in progression down to molecular structure of one leaf, and on to chromatin, DNA, and subatomic particles.

Item Type: Image Set
Duration: 15 minutes

#### Student Tutorials:

This unique website compares the magnitude and size of a broad variety of objects, using colored histograms for ease of visual comparison. Objects range from the nanoscale to distances between galaxies.  Most items are linked to annotated reference pages.

Item Type: Online Tutorial
Duration: 30 minutes

### Physics Terminology (2)

#### Activities:

If you've never visited the award-winning Hyperphysics web site, put it on your list. It is a set of online tutorials that features concept maps laid out in a web-like fashion for easy navigation. This page describes units of measurement, unit conversions, dimensional analysis, and basic mechanical quantities. Some of the maps are "active graphics", which link to capsules of background information. Remarkably easy to use!

Item Type: Reference Material
Level: Teacher Support

#### Student Tutorials:

To a beginning student, the unfamiliar language of physics can seem like a foreign tongue. This tutorial, part of the respected Physics Classroom collection, is an interactive introduction to some basic terminology. It focuses on scalars, vectors, distance, and displacement.

Item Type: Interactive Tutorial
Duration: 30 minutes

### Units of Measure (5)

#### Activities:

This item provides rules and "how-tos" for calculating both the relative and absolute uncertainty in a measurement.

Item Type: Tutorial
Level: Teacher Support

This resource is a digital tool for performing unit conversions with the extra feature of displaying cancellation of terms, helping students to gain a deeper understanding of the mathematical processes involved.  Students can convert among 25 physical quantities, including units such as force, temperature, energy, and current.

Item Type: Mathematical Tool

#### References and Collections:

All mechanical quantities can be expressed in terms of three quantities: length, mass, and time. This item is part of the highly-regarded Hyperphysics concept maps. It describes units of measurement, unit conversions, dimensional analysis, and basic mechanical quantities. Some of the maps are "active graphics", which link to capsules of background information. Remarkably easy to use!

Item Type: Reference Material
Level: High School

NIST, the National Institute of Standards and Technology, publishes this set of in-depth reference materials, covering 3 topics:  1) Fundamental physical constants, 2) International System of Units (SI), and 3) Uncertainty in measurement.

Item Type: Reference Material
Level: Teacher Support

Teachers will find in-depth information on base units, derived units, and relationships among SI units in this free web site developed and maintained by NIST (the National Institute for Science and Technology). Don't miss the link to the "Digital Dutch" unit converter.  It is amazingly easy to use.

Item Type: Reference Material
Level: Teacher Support

### Applying Measurement in Physics (8)

#### Lesson Plans:

An exceptional resource collection on how to integrate "direct measurement videos". These high-speed short videos feature tools for easy analysis of various physical situations:  rulers, grids, frame-counters, and screen overlays for making precise measurements. Includes 9 teaching modules with lesson plans, assessments and answer keys, and pedagogical background. Does not require purchase or installation of video analysis software.

Item Type: Video Analysis Lessons

#### Activities:

This cost-free web page allows teachers and learners to easily create and print graphs for use as visual communication tools.  With one click, the students may choose from five graph types: bar, line, area, pie, and X/Y.  Various patterns, colors, grids, and label choices are available to allow customization.

Item Type: Graph-Making Tool

After introducing the rules of significant figures, students can test their skills in this interactive drill & skill. We suggest setting up cooperative learning groups to make it a game.  NOTE FROM THE EDITOR: beginning students often misunderstand or overestimate the usefulness of significant figures. In real-world research laboratories, practicing scientists commonly express uncertainty quantities as a separate numeral. Good examples of how to express uncertainty can be found in the NIST Fundamental Physical Constants (Reference below).

Item Type: Problem Set
Level: High School
Duration: 30 minutes

How small is the error between two and three significant digits? How about three and four digits? Can the error be ignored? This activity would be a great choice for students who have already been exposed to the basics of significant figures. They enter a number, then select the number of significant digits from 1-5. The resultant numbers are automatically displayed, plus the percent error.

Item Type: Interactive Problem Set
Level: High School
Duration: 30 minutes

This is a really nice interactive simulation to give students virtual practice in using a micrometer, a device for doing ultra-precise measurement down to the level of 1 micrometer. Each time the "reset" button is pressed, a random-size object appears on screen. Students use sliders to move the object into place, perform the measurement, and check the accuracy of their reading.

Item Type: Interactive Simulation
Duration: 30 minutes

#### References and Collections:

Values of the fundamental physical constants, recommended for international use, are provided at this web site. These are the latest values of the constants recommended by CODATA (updated in 2006).  Need background information?  It's all there, in an easily-searchable format.

Item Type: Reference Material

#### Student Tutorials:

This item, part of the Open Door website, discusses the role of uncertainty in measurement.  Students learn the difference between systematic and random error, and gain practice in quantifying the error.  Also find high-quality sections on the Vernier scale, "best-fit line", and sampling frequency.

Item Type: Online Tutorial
Level: High School
Duration: One class period

Measurement of physical objects is, by nature, imprecise. When rounding numbers, you must use enough digits to minimize errors.  However, if too many digits are used, errors can be easily made keeping track of all the numerical values. This tutorial will help students with the basic rules.

Item Type: Interactive Tutorial
Level: High School
Duration: 30 minutes

### For the New Teacher (3)

#### Activities:

This digital unit converter offers students more than the typical online conversion resource.  It allows conversion among 25 physical quantities, from more common applications (force, energy, current, voltage) to lesser-used conversions such as illuminance and magnetic flux.  It provides the additional feature of displaying cancellation of terms, helping beginners to gain a deeper understanding of the mathematical processes involved.

Item Type: Mathematical Tool

#### References and Collections:

This resource is a comprehensive guide on SI for teachers and students.  It contains tables, charts, and text explanations of base units, derived units, equivalencies, common quantities, and prefixes.  To aid the learner in visualizing quantities, drawings of common multiples are provided for each of the base units.  The materials are written so that a user with no prior experience with metrics can comprehend the measurements and how they are applied mathematically.

Item Type: Reference Material
Level: Teacher Support

#### Content Support For Teachers:

This item, part of the Open Door website, discusses the role of uncertainty in measurement.  Review the difference between systematic and random error, and gain practice in quantifying the error.  Also find high-quality sections on the Vernier scale, "best-fit line", and sampling frequency.

Item Type: Online Tutorial
Level: Teacher Support

### Teaching Tools (5)

#### Activities:

A helpful online unit converter for teachers and students.

Item Type: Mathematical Tool

This cost-free web page allows teachers and learners to easily create and print graphs for use as visual communication tools.  With one click, the students may choose from five graph types: bar, line, area, pie, and X/Y.  Various patterns, colors, grids, and label choices are available to allow customization.

Item Type: Graph-Making Tool

This newer and beautifully designed version of Powers of 10 takes students on a "nano-journey" inside a carbon-based cell, an LED diode, and a laptop microchip. At each descending level, you can click on background information and additional Flash simulations. Kids can choose from 3 images and send "postcards" to friends about their journey. Fair warning:  this resource is so engaging, be prepared to spend at least an hour on your trip.

Item Type: Interactive Animation
Duration: One Class Period

#### References and Collections:

A site that lists the constants with all types of units and gives a tutorial on calculating uncertainty.

Item Type: Reference Material
Level: Teacher Support

#### Content Support For Teachers:

A good resource that gives the teacher tools to get at students' prior knowledge about measurement and uncertainty.

Item Type: Scholarly Article
Level: Teacher Support

### Dimensional Analysis (3)

#### Content Support For Teachers:

This web page is part of the highly-regarded Hyperphysics concept maps. It describes units of measurement, unit conversions, dimensional analysis, and basic mechanical quantities. Some of the maps are "active graphics", which link to capsules of background information. Remarkably easy to use!

Item Type: Reference Material
Level: Teacher Support

#### Student Tutorials:

Dimensions of a quantity refer to the combination of units or base quantities that make it up. Most physical quantities can be expressed in terms of five basic dimensions and their combinations: mass, length, time, electrical current, and temperature. Often, students have difficulty understanding why dimensions are different than units. This tutorial contains basic information, 3 short quizzes and one longer post-test. Your students can move at their own pace or work in cooperative groups. **NOTE: This activity can be done without computers, as all components are printable.

Item Type: Instructional Module
Duration: 2-3 class periods

#### Assessment:

This resource is a formal study assessing student understanding of measurement and uncertainty.  It was administered to more than 500 students at two large research universities to address these questions:  1)  How does student understanding change over one semester from participating in an introductory physics course with a lab, and 2) What patterns exist in student reasoning pertaining to measurement and uncertainty prior to instruction?

Item Type: Scholarly Article
Level: Teacher Support

### Scale, Order of Magnitude, and Estimation (4)

#### Activities:

Students explore size estimation in 1, 2, and 3 dimensions. Multiple levels of difficulty allow for progressive skill improvement. CAUTION: This activity is addictive!

Item Type: Interactive Animation
Duration: One class period

An updated version of "Powers of 10".  View the Milky Way at 10 million light years from Earth, then move through space at successive orders of magnitude until you reach an oak tree in Florida. After than, move from a single leaf to the cell nucleus, chromatin, DNA, and subatomic particles.

Item Type: Image Set
Duration: 15 minutes

Interactively explore various specimens as they appear under a scanning electron microscope (SEM).  SEM can produce very high-resolution photos of details as small as 1-5 nanometers. Students can adjust the focus, brightness, and contrast, and choose from a cockroach, pollen grain, diatom, a gecko foot, a jellyfish, and more. Each successive image doubles the magnitude of the magnification.

Item Type: Images/Illustrations
Duration: 30 minutes

This newer and beautifully designed version of Powers of 10 takes students on a "nano-journey" inside a carbon-based cell, an LED diode, and a laptop microchip. At each descending level, you can click on background information and additional Flash simulations. Kids can choose from 3 images and send "postcards" to friends about their journey. Fair warning:  this resource is so engaging, be prepared to spend at least an hour on your trip.

Item Type: Interactive Tutorial
Duration: One Class Period

### Assessments (2)

#### References and Collections:

The National Assessment of Educational Progress (NAEP) is the only nationally administered, continuing assessment of what America's students know and can do in various subject areas.  This website provides free access to the most recent assessment questions, organized by topic and level. Teachers can view an analysis of the results to see short-term and long-term trends in samples of students at ages 9, 13, or 17 years.

Item Type: Assessment Tool