Transcript
ExploringTime
Exploring Time: Hour2 MS Activity Central Concepts: Sequencing, time scales, scientific notation Objectives: o Students will analyze sequential changes in order develop an understanding of how things change over time. o Students will utilize scientific notation in working with large and small numbers. Time: Two, 60-minute class periods I.
OVERVIEW Students will be given a printout containing images from a video clip or animation showing an event over time. Students are challenged to place the images in the proper chronological order. Each set of images depicts an event over a different timescale (i.e. formation of solar system, heart beat, brain pulses, hummingbird flying etc.). Throughout the activity, students will be using standard and scientific notation to try to conceptualize very short time scales.
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BACKGROUND A.
Time scales “Each time scale is a new window on the world.” Scientists who study changes that take place over very large or very small timescales think differently about time than the average person. What would signify a short or long amount of time to them is relative to the average duration of the processes that they study. For a climatologist like Lonnie Thompson who studies glaciers, a century might seem like a small amount of time. For a Particle Physicist like Fulvia Pilat, a minute is an eternity. Time-lapse imaging and digital modeling allow scientists to study and demonstrate changes happening at large and small time scales. By doing so, they can better understand the overall dynamics of the intricate web of the earth systems, and can interpret processes and make predictions to advance scientific understanding. Part 2 of Exploring Time examines how scientists study events taking place over smaller time scales ranging from a single second to a billionth of a second. It continues to analyze the reasons why scientists conceptualize their work in time scales, and why understanding events at these scales aids in scientific understanding. 1.
Small Time Scale Terms millisecond, (ms or msec), one thousandth (10 –3 ) of a second microsecond, (µs), one millionth (10-6) of a second nanosecond, (ns or nsec), one billionth (10-9) of a second picosecond, (ps) one trillionth (10-12) of a second femtosecond, (fs), one quadrillionth 10-15 of a second • attosecond, one quintillionth (10-18) of a second • • • • •
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Large Time Scale Terms Annum: Latin term meaning year Giga annum (Ga)= billion years ago Mega annum (Ma) = million years ago Kilo annum (ka) = thousand years ago
B. Moving Images All moving images, (including movies, cartoons and animations) are created by showing a sequence of still images (frames). Each frame is typically slightly different than the previous. When viewed sequentially at high speeds, the viewer perceives movement. This happens because the human eye cannot detect changes between photographs at this rate and combine the images together. This is called persistence of vision or flicker fusion rate. The human eye can begin to detect individual frames at a rate of about 16 frames per second. Most movies are filmed at 24 frames per second. C. Other Important Terms Circadian rhythms Arrhythmia Frame
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MATERIALS Per teacher • Lighter or matches Per group of students • 1 Sequence Set of 5-10 images for each event (see Teacher Prep) • overhead or dry-erase markers (for labeling the laminated photos) • stopwatch
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STANDARDS GRADES 5-8 A. Abilities necessary to do scientific inquiry 1. Communicate and defend a scientific argument 2. Use mathematics and technology to improve investigations and communications 3. Understandings about scientific inquiry B. Content Standard F: Science in Personal and Social Perspectives 1. Science and technology in society
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WEBSITES A. Information on high speed photography 1. http://www.hiviz.com/ Information on high-speed photography and imaging especially for teachers, students, photographers, and electronics hobbyists. 2. http://en.wikipedia.org/wiki/High_speed_photography
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ExploringTime 3. http://en.wikipedia.org/wiki/Slow-motion B. Other helpful sites: 1. http://www.youthcentral.vic.gov.au/Jobs+&+Careers/Career+profiles/Media ,+arts+&+entertainment/High-speed+Photographer/ High-speed photographer career profile 2. http://folding.stanford.edu/ Link to Dr. Vijay Pande’s protein folding site mentioned in the episode. 3. http://www.shortcourses.com/how/flipbooks/flipbooks.htm An instructional site for making flipbooks.
TEACHER PREP
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1. Review the Exploring Time website www.exploringtime.org 2. Review the image set available on the website from the video “Balloon Slice.” You may want to make an answer key of the correct order. 3. Print and laminate (for reuse) a Sequence Set for each group of students.
4. Preview Exploring Time: Hour 2. If you do not have a copy of the DVD, you can view
the show in segments on the website (go to The Show/Segments). During this activity, you will be stopping the video in several places to check for student understanding and to complete the related activities. These places are noted in the Procedure sections. While you are watching the video prior to the lesson, take note of these places and decide if there are additional stopping points you may need to enhance student understanding. You also may want to download the transcripts of the Exploring Time show, which are also available on the Segments page.
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PROCEDURE:
A. Engagement 1. Strike a match or light a lighter in front of the class. Ask the students to tell you the steps in that process—the sequence of what they observed. They will probably be able to state the major observable actions—your thumb rolls the striker and depresses the button to release fuel, flame lights, etc. Ask them to describe the moment of combustion. When they have trouble with this, ask the students why they can’t describe it. (It happens too fast to see.) 2. Hand out stopwatches to each pair of students. Ask them to time the other person blinking. When they can’t capture it, ask them how they think scientists study these super-fast actions. 3. Ask the students to list actions or processes they know of that are too fast to observe (i.e. insect wings in flight, gun firing, racket hitting a ball, etc) . 4. Ask students to discuss their thoughts about how scientists are able to study these high-speed actions, ones that the human eye can’t directly or precisely observe. (They slow them down through high-speed photography, image models, etc.) 5. Show the class the “Lighter” video from the Exploring Time website. You may also want to show additional slow motion clips such as “Light Bulb Burst” or “Eye Blink.” 3
ExploringTime 6. Explain that today they are going to watch a video about how scientists study the world of the super-fast and engage in some activities with high-speed images. B. Explore and Explain 1. Begin watching the episode, Exploring Time: Hour 2. Watch Segment One: An Introduction to Smaller and Smaller Time Scales. 2. Discuss what the students have found interesting so far. 3. Begin to discuss the idea of different time scales and how we represent them mathematically. Ask if the students know when the dinosaurs went through a major mass extinction. (~65mya) Ask a student to write that number on the board in scientific (6.5 x106) and standard notation (65,000,000). Now ask them how long ago the civil war ended. (1865, 132 years ago) Write that on the board in both notations. Then ask them to write their ages in scientific notation. 4. Explain that the rest of the episode will focus on much shorter spans of time. 5. Watch the next two segments of the video: Human Perception of Time from Days to Hours, and Hours to Seconds. 6. Explain that now they are going to reflect on events that take place at the time scale of days. Show them the video Beard Growing from the Video Archive on the website. Ask them to think of other changes that are observable over the span of days. 7. Tell students that they will now learn more about processes that happen on fast time scales. Watch the next two segments: Seconds to Tenths of a Second, and Tenths of a Second to Milliseconds. Ask the class to blink, and tell them that that duration was approximately 0.5 (5/10ths, 5x10–1) seconds. Ask them how to write that in scientific notation. 8. Hand out the Sequencing Sets of images from the “Water Balloon Slice” video. Repeat steps four and five. 9. After watching the next two segments: Milliseconds to Microseconds and Microseconds to Nanoseconds, and have several students write the following numbers out in standard and scientific notations on the board: • millisecond, (10 –3 ) • microsecond, (10-6) • nanosecond (10-9) • picosecond (10-12) • femtosecond (10–15) • attosecond (10–18) Discuss these numbers. Answer any questions the students have. 10. Complete the viewing of the episode. Discuss student questions and ideas about the episode.
VIII. EXTENTIONS A.
After the students have watched the complete video, construct a graphic organizer that outlines the times scales and processes highlighted in the film. Here is an example:
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Seconds millisecond microsecond nanosecond picosecond
femtosecond
attosecond
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After they complete a graphic organizer, have them consider ways scientists conceptualize time when studying short time scales. …to study phenomena at very short time scales, scientists often rely on high speed imaging in order to capture data about changes occurring too quickly for human eyes to see.
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ADDITIONAL ACTIVITIES Build a Zoetrope Objective: Students will build a zoetrope to view the flipbook as a movie A zoetrope is a relatively easy device to build that allows the viewer to see still frames as moving images. For more information on zoetropes, visit:
• http://www.randommotion.com/html/zoe.html •
http://courses.ncssm.edu/GALLERY/collections/toys/html/exhibit10.htm
or one of these for building instructions: •
http://www.groeg.de/puzzles/zoetrope.html This site has a link to a PDF file of a blank template.
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http://bizarrelabs.com/zokit.htm
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http://www.instructables.com/id/ELHBPVD1D5EP2866EE/ Uses a lip balm container and a CD 5
ExploringTime 1. Have students research zoetropes. Students can make their own zoetrope with images from the lesson. 2. Extension: As a home project, students can take their own time-lapse images and build a zoetrope with their images. Some questions might include: •
Did you speed up or slow down your action.
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How did changing the time scale help you observe the process of your action?
Research Projects 1. Students will research how the human visual system and mind detect change. Possible topics:
Flicker fusion rate
Persistence of vision
2. Students will research the history of moving picture development. Possible topics:
Movies
Cartoons
Computer animations
Tweening
3. Students will research methods for dating and detecting long-term change. Possible topics
Radiocarbon dating
Dendrochronology (tree ring dating)
Sediment and hard-rock cores
Ice cores
Biostratigraphy
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