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Fall 2016, Phys 131, Reminder from 9-30

Page history last edited by Kim Moore 3 years, 7 months ago

TA/LA Training Reminders from 9/30/2016, for the week of 10/03 (Lab 2, Part 2)


Here are the reminders that I promised you regarding the Lab/Recitation training.  Good luck this week! ~KIM


1) Recitation: Propelling a Paramecium

Link: http://umdberg.pbworks.com/w/page/58647864/Propelling%20a%20Paramecium%3A%20Recitation

***The papers for the recitation are "Do not write on. Do not remove."  If supplies run low, contact Kim ASAP.


(Break--Pass back Lab 1, Part 2 if not returned last week...)


2) Lab 2, Part 2: Directed Motion & Resistive Forces

Link: http://umdberg.pbworks.com/w/page/68933700/NEXUS%20Physics%20Labs%2C%202013-2014


*** When you have the Lab 1, Part 2 grades ready for your students, please hand back the reports.  All students should have their labs graded and back in their hands before they turn in their next lab.  (So hand them back at the start of lab during the week of Oct. 3rd, at the latest.)  I always tell the students that "The Checker keeps the lab," that way each student has one example of a graded lab in their possession by the end of the semester.  Do it however you like (perhaps the Journalist keeps it), but be consistent within your own sections. 


a) Before the students resume last week's work, it is helpful to encourage them to PLAN their data analysis (and error analysis).  Too often, beginning experimenters dive into the data analysis with no clear plan in mind.  This can cause false trails, repeated work, and wasted time.  It is MUCH more efficient to spend a little time planning the analysis at the very start, talking through how to get the pixel and frame information into a terminal velocity and how to use the terminal velocities to construct displays of their data (i.e., graphs) to aid them in finding conclusions for each part of the investigations, than it is to start the analysis with no plan in mind.


b) Last week, students should have: modeled the situation, designed their experiments, collected the videos, and harvested ALL the videos using ImageJ, including finding a measure of uncertainty at terminal velocity for each video collected and the distance -to-pixel ratio for each video.  This week, students should: determine how to analyze their data, analyze the data--including error analysis, draw conclusions for both parts of the investigation, and finalize the lab report discussing their investigations and their findings.  This is a LOT to do, so all group members need to be actively engaged in helping the group achieve its goals.


c) Remind the students that the uncertainty, average rate, and pixel-to-distance conversion will be UNIQUE to EACH VIDEO!  If they have not yet collected uncertainty info for their videos, they should do so ASAP.


d) Students should not need to take more data in this second week, but the equipment is available, should the need arise.  Remind groups using the equipment of the safety precautions discussed for week 1 of this experiment.


e) There is data about the masses (given in the Lab 2, Part 2 TA Guide, and given as SETS of equipment--multiple balls and multiple filters) that students will need for the plots in the 1st investigation.  Do not provide this information to individual groups until the groups make a specific request.  Realizing that information is missing that is needed for the analysis is an important part of careful scientific reasoning in this lab.  Giving the mass information away too soon robs the students of the chance to fully engage in a reasoned analysis.  If you eventually write this information on one of the TA whiteboards, be sure to ERASE it again before you leave the room (to help prepare the room for the next TA).


f) The error analysis in this lab should involve some error propagation.  The students have been required to read the "Intro to Error Propagation" technical guide as a pre-reading for this week of Lab 2.  Additional copies are available at the back of the room (and should STAY in the room for other students to use).  Students will have several opportunities to practice error propagation, in both 131 and 132, but they should definitely start today!  Our main emphasis with error analysis is that there are MANY correct ways to do error analysis--so long as the choices you make match the decisions you have made in data collection and data analysis.  Given the equipment available and the type of data produced, error propagation is a good match for this lab (thus we take a week to emphasize this skill).  Students may need help thinking about which terms contribute most, what numbers to substitute into the final formula, and what to do with the resulting uncertainty (which produces information used to put individual error bars on the vertical data plotted on the terminal velocity vs. mass, terminal velocity squared vs. mass, and terminal velocity vs. viscosity graphs).  These uncertainties can help us choose among the available models for describing our data--i.e., they can help us pick the appropriate scaling relationship.


g) Please have students clean up after themselves before leaving the lab room--wiping up any spills and throwing out the paper towels, putting equipment back where it belongs, and sorting and stacking the recitation and lab documents at the back of the room.  They should also erase their whiteboards. If the whiteboards become hard to use, due to the glycerol, then there are whiteboard wipes available for cleaning them.


h) When your section's lab reports are in your hands, please bring them to Kim in room 1322 for scanning.  She will get these back to you ASAP.


i) If paper or staples run low, see Bill or Omar for more materials.


Please let me know if you have any questions or comments!


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