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| | {{Cover|2.1 Senses and Instrumentation}} |
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| Science uses both our direct senses and a variety of instruments to extend our ability to observe phenomena. We trust our instruments for the same reasons we trust our senses; interactive exploration and comparison.
| | "Seeing is believing," but should I believe what I see through a telescope? Or the reading I see on a thermometer? Instruments extend our experience of the world beyond our senses. Just as with our senses, we gain trust in scientific instruments through interactive exploration and comparison. |
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| == The Lesson in Context == | | == The Lesson in Context == |
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| This lesson links the idea that there's a shared reality "out there" and the beginnings of our comprehension about it. It does this by providing the foundation for why we can trust that the instruments we use are in fact measuring something real about reality. The lessons after this are about how we interpret the results of our measurements and start to unpack what they're actually telling us about reality. | | This lesson links the idea that there's a shared reality "out there" and the beginnings of our comprehension about it. It does this by providing the foundation for why we can trust that the instruments we use are in fact measuring something real about reality. The lessons after this are about how we interpret the results of our measurements and start to unpack what they're actually telling us about reality. |
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| <!-- Expandable section relating this lesson to earlier lessons. --> | | <!-- Expandable section relating this lesson to other lessons. --> |
| {{Expand|Relation to Earlier Lessons| | | {{Expand|Relation to Other Lessons| |
| | '''Earlier Lessons''' |
| {{ContextLesson|1.2 Shared Reality and Modeling}} | | {{ContextLesson|1.2 Shared Reality and Modeling}} |
| {{ContextRelation|Senses and instruments as means to study the shared reality.}} | | {{ContextRelation|Senses and instruments as means to study the shared reality.}} |
| {{ContextRelation|Ways to help us feel "real" about things we can't directly see.}} | | {{ContextRelation|Ways to help us feel "real" about things we can't directly see.}} |
| }} | | {{Line}} |
| <!-- Expandable section relating this lesson to later lessons. -->
| | '''Later Lessons''' |
| {{Expand|Relation to Later Lessons|
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| {{ContextLesson|2.2 Systematic and Statistical Uncertainty}} | | {{ContextLesson|2.2 Systematic and Statistical Uncertainty}} |
| {{ContextRelation|Accept that instruments are inaccurate or imprecise.}} | | {{ContextRelation|Accept that instruments are inaccurate or imprecise.}} |
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| {{ContextRelation|The value of interactive exploration can be understood in terms of causation as "correlation under intervention."}} | | {{ContextRelation|The value of interactive exploration can be understood in terms of causation as "correlation under intervention."}} |
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| == Takeaways == | | == Takeaways == |
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| </tabber> | | </tabber> |
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| == Useful Resources ==
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| <tabber>
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| |-|Lecture Video=
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| <br /><center><youtube>uYravgWpl6o</youtube></center><br />
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| |-|Discussion Slides=
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| {{LinkCard
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| |url=https://docs.google.com/presentation/d/1-OUFoZqiYErsLwBxaUkOk-R0AmsnfdlZOrpKinlxFgk/
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| |title=Discussion Slides Template
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| |description=The discussion slides for this lesson.}}
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| <br />
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| |-|Handouts and Activities=
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| {{LinkCardInternal
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| |url=:File:Senses and Instrumentation - Worksheet.pdf
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| |title=Interactive Exploration Worksheet
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| |description=Worksheet used for all the activities in this lesson.}}
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| {{LinkCard
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| |url=https://apps.apple.com/us/app/spectrumview/id472662922
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| |title=iOS Spectrogram App
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| |description=iOS app used for the spectrogram activity.}}
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| {{LinkCard
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| |url=https://play.google.com/store/apps/details?id=github.bewantbe.audio_analyzer_for_android&hl=en_US&gl=US&showAllReviews=true
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| |title=Android Spectrogram App
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| |description=Android app used for the spectrogram activity.}}
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| <br />
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| |-|Readings and Assignments=
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| {{LinkCardInternal
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| |url=:File:Do We See Through a Microscope - Hacking.pdf|Do We See Through a Microscope?
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| |title=Do We See Through a Microscope?
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| |description=Do you think you "see" through an ordinary microscope? What about an electron microscope? Does using the word "see" imply that what you see is what is really there?}}
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| <br />
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| </tabber>
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| == Recommended Outline ==
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| === Before Class ===
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| * Have students download a [[#Useful Resources|spectrogram app]] on their phones for [[#Spectra of Sound|the first activity]].
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| * Review and print worksheets for students.
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| * Get all materials for activities:
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| ** Slinkies (may need a weight with each, one per group)
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| ** Gas lamp (also called a discharge tube) (any kind will do, one per class)
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| ** Diffraction grating (one per person)
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| * If you want, bring a musical instrument to class to use with the spectrograph.
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| === During Class ===
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| {| class="wikitable" style="margin-left: 0px; margin-right: auto;"
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| |1 Minute
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| |Hand out worksheets.
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| |1 Minutes
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| |Introduce the lesson and go over the plan for the day. Make sure people have groups, spokespeople, etc.
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| |3 Minutes
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| |Ask the [[#Warm-up Question|warm-up question]] to loosen the students up and get them ready to be convinced of their capacity to understand reality.
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| |20 Minutes
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| |Do [[#Spectra of Sound|activity 1]] (sound spectra).
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| |-
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| |20 Minutes
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| |Do [[#Spectra of Light|activity 2]] (light spectra).
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| |20 Minutes
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| |Do [[#Slinky Drop|activity 3]] (slow motion camera).
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| |15 Minutes
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| |Ask the [[#Final Discussion Questions|post-activity discussion questions]].
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| |}
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| == Lesson Content ==
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| {{BoxWarning|This is a logistically heavy lesson. Make sure to prepare far in advance to plan and prepare the necessary materials. You may need to contact your institution's physics demo office.}}
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| === Warm-up Question ===
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| Which statement best captures your stance?
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| <ol style="list-style-type:lower-alpha">
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| <li>I think our understanding of reality is mostly wrong.</li>
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| <li>I think most of our understanding of reality is mostly wrong, but we might have a few bits basically accurate or close to accurate.</li>
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| <li>I think a good bit of our understanding of reality is probably generally accurate or close to accurate, with a lot of errors.</li>
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| <li>I think most of our understanding of reality is mostly accurate or close to accurate, with some important errors.</li>
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| <li>I think nearly all of our understanding of reality is accurate, with few important errors.</li>
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| </ol>
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| {{BoxTip|This question has no "correct" answer, but it's nice to get a sense of where your students stand and have them argue their responses with each other.}}
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| === Spectra of Sound ===
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| [[File:Cropped Android Button.png|thumb|Instructions for Android users.]]
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| In this activity, students use a [[#Useful Resources|spectrogram app]] on their phones to interactively explore the frequency composition of different sounds and voices. Seeing the spectrogram immediately and consistently respond to different sounds should give the students a sense that it's measuring something real.
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| {{BoxCaution|To make the Android app display readings in the same way as the iOS one, students may have to push the button that says "1D" at the bottom of the screen. This switches the app to "2D" mode.}}
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| ==== Instructions ====
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| Prior to class, make sure the students download one of the [[#Useful Resources|spectrogram apps]] on their phones.
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| {| class="wikitable" style="margin-left: 0px; margin-right: auto;"
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| |2 Minutes
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| |Introduce the activity by opening the app on your phone and singing or whistling out loud into it. But, don't show them the results of your measurement.
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| |10 Minutes
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| |Have the students explore different sounds with the apps. They will investigate the sounds of their singing/whistling and different voices/sounds as well as high and low pitched notes from any musical instruments if they have them available. Encourage them to look at the differences between the spectra for the different voices and sounds.
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| |4 Minutes
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| |Have the students discuss the [[#Sound Discussion Questions|discussion questions]] in small groups.
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| |4 Minutes
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| |Discuss [[#Sound Discussion Questions|the questions]] as a class. You can skip this step if you're running short on time.
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| |}
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| ==== Sound Discussion Questions ====
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| # Based on your observations, how could you distinguish the various sounds, if you were given the spectrogram alone (but not your own sense of sound)?
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| # How do you know that the instrument is showing something real about the world? How does ''interaction'' help you test it?
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| === Spectra of Light ===
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| This activity has students use small diffraction gratings to look at the spectrums produced by various light sources. By interactively observing the different patterns diffracted out by different types of lights, the students should be able to see that there is some structure to light that they can't easily observe with their naked eyes. The students can trust their instruments because they see the results consistently and in direct response to their measurements.
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| <center><youtube>O5pvO5BPvF4</youtube></center>
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| ==== Instructions ====
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| {| class="wikitable" style="margin-left: 0px; margin-right: auto;"
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| |2 Minutes
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| |Get everyone set up with their diffraction gratings and demonstrate looking through one. If you don't have access to diffraction gratings, you can use old CDs.
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| |-
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| |10 Minutes
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| |Have the students look at different sources of light. They should try looking at the sunlight (but not at the sun directly), any lamps in the room, and the LED lights on a phone or other electronic device. If you have special lamps from the physics department, have them look at those too.
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| |-
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| |4 Minutes
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| |Have the students discuss the [[#Light Discussion Questions|discussion questions]] in small groups.
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| |4 Minutes
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| |Discuss [[#Light Discussion Questions|the questions]] as a class. You can skip this step if you're running short on time.
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| |}
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| ==== Light Discussion Questions ====
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| * What do you see through the grating that differentiates the different light sources?
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| * How can you interact with this grating film/CD to assure yourself that the instrument is showing something real about the world?
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| * Based on your observations, how could you distinguish the various light sources, if you were given the diffraction grating film alone (but not your actual sense of vision)?
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| {{BoxTip|title=Hint|Light can warm things up.}}
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| === Slinky Drop ===
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| For this activity, each group will need one slinky and one smartphone with slow motion camera capability.
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| <center><youtube>AjDc-KPX15E</youtube></center>
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| {{LinkCard
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| |url=https://www.youtube.com/watch?v=k5s1cMNTmGs
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| |title=How a Slinky Falls in Slow Motion
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| |description=Additional video explaining the phenomena in this lesson.
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| }}
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| ==== How to Drop ====
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| {{BoxTip|These and all other instructions for the activity are provided in the [[#Useful Resources|handout]].}}
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| # Hold on to one end of the slinky and let the whole slinky naturally hang down. The bottom of the slinky should not touch the ground. If the slinky is too long, you may hold onto many rings at once, so that the remaining length does not touch the ground.
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| # Once the slinky is steady (not bouncing or swinging), release it to let it to fall to the ground.
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| ==== Slinky Question 1 ====
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| What is happening to the bottom of the slinky just after you release it?
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| <ol style="list-style-type:lower-alpha">
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| <li>It is falling at the same speed as the top of the slinky.</li>
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| <li>It is falling slightly slower than the top of the slinky.</li>
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| <li>It is falling slightly faster than the top of the slinky.</li>
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| <li>{{Correct|It is not falling at all.}}</li>
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| <li>It is moving upwards.</li>
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| </ol>
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| ==== Slinky Question 2 ====
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| What is happening to a ring in the middle of the slinky just after you release it?
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| <ol style="list-style-type:lower-alpha">
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| <li>It is falling at the same speed as the top of the slinky.</li>
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| <li>It is falling slightly slower than the top of the slinky.</li>
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| <li>It is falling slightly faster than the top of the slinky.</li>
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| <li>{{Correct|It is not falling at all.}}</li>
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| <li>It is moving upwards.</li>
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| </ol>
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| ==== Next Steps ====
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| # Have other group members repeat this.
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| # Now, with one person holding the slinky as in [[#How to Drop|the first drop]], have a second person record a slow motion video of the slinky from a distance using a smartphone camera.
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| # As a group, review the slow motion video and answer the above questions again.
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| {{BoxTip|You can maximize slowness on iPhones by clicking the number in the upper right corner from 120 to 240 (frames per second). Other phones may have "slo mo" and "super slo mo" options. Make sure the video includes the entire slinky and the floor. Keep the camera steady throughout the recording.}}
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| ==== Play Around ====
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| What else can you do with a slinky? Can the slow motion camera help you see other movements of the slinky more clearly? (E.g. stretch out the slinky between two people and have one person jolt it, while a third person records.) Feel free to play around and experiment. How does your interactive exploration of the slo mo videos of the slinky help you believe the video is showing what's happening AND reveal how the slinky is really moving?
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| {{BoxTip|Skip playing around if you're running short on time.}}
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| === Final Discussion Questions ===
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| ==== Question 1 ====
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| In all the instruments we've looked at, we've directly compared them with our senses. How do we check our senses when we are unsure of them? How do we do that for our instruments?
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| {{BoxAnswer|Our senses can be validated just like any other instrument. Since the things we see, hear, smell, touch, and taste allow us to navigate through the world, for which those senses are our only direct input, and they tend to line up with each other, they have some stability and reliability. And, as with testing instruments against each other, we can compare our senses with the observations of others (shared reality!). Since they tend to fit with the reports of others, for the most part, that is our shared reality, such as it is. (Whatever else we might mean by 'reality,' it's hard to say it's not all the stuff that seems to have similar effects on us and everyone else we talk to and observe.)</br></br> Furthermore, no instrument needs to be 100% accurate to tell us something about the world. As long as there is some regime in which some of our senses work, we can use that as a basis to start validating other tools and exploring some aspect of the world.}}
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| ==== Question 2 ====
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| How can we observe a thing that we can never perceive directly with our senses?
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| {{BoxAnswer|We can build up an "instrument ladder" by comparing and building on results from previous instruments we've already tested. Instead of validating with our direct senses, we can validate with other instruments that were in turn validated by even more instruments as long as at some point the bottom rung of the "ladder" was validated with our senses, which were in turn validated against each other.}}
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| ==== Question 3 ====
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| Not all instruments are as directly interactive as the ones we've used here. Describe an entity which you believe exists for which you have only very indirect evidence.
| | {{#restricted:{{Private:2.1 Senses and Instrumentation}}}} |
| # Why do you believe it exists? | | {{NavCard|chapter=Lesson plans|text=All lesson plans|prev=1.2 Shared Reality and Modeling|next=2.2 Systematic and Statistical Uncertainty}} |
| # Is there anything that might convince you it did not exist?
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| # Is there anything that might convince you that although something like it does exist, it has quite different properties than you had thought?
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| {{BoxTip|title=Examples|Electrons, quarks, black holes, dark matter, etc.}}</restricted>{{NavCard|prev=1.2 Shared Reality and Modeling|next=2.2 Systematic and Statistical Uncertainty}} | |
| [[Category:Lesson plans]] | | [[Category:Lesson plans]] |
