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Rethinking our goals: What will our students remember when
they forget everything?Eugenia Etkina
Graduate School of EducationDepartment of Learning and Teaching
Rutgers UniversityAAPT-PERC 2010 Portland, Oregon
Former and present members of the Rutgers PER group who contributed to this work
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A. Van Heuvelen, S. Brahmia, M. Ruibal -Villasenor, M. Gentile, G. Suran
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D. Brookes, S. Murthy, D. Rosengrant,A. Warren, A. Karelina, V. Shekoyan
What is physics?
• Body of knowledge
• A process through which this knowledge is constructed and constantly refined
What do we often focus on when we think of learning or teaching physics?
• Body of knowledge
If we think of an analogy
Athletic body
Process is the key
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What is this process?
What do physicists do when they do physics?
Physicists
• represent physical processes and ideas in different ways
• design experimental investigations
• collect and analyze data
• devise and test ideas (mathematical models, mechanisms, etc.)
• modify their ideas in light of new data
• evaluate
• communicate
• Work together and do it again and again
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Are those processes that we need to teach?
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Observe
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Observe
Hypothesize
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Observe
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Hypothesize
Predict
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Observe
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Hypothesize
Predict
Test
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Do it again and again until I am satisfied
Children are born physicists who do not give up
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Can we capitalize on this?
Why should we?
Why should we focus on the process?
Our students will encounter different elements of the physics body of knowledge in the course ONCE but if we focus on the process then there are MULTIPLE opportunities to see the same process again and again. + They were good at it at some point.
Can we use the physics body of knowledge as a context to help students strengthen the “physics habits of mind” that they already have?
Investigative Science Learning Environment (ISLE)Etkina and Van Heuvelen, 2001
+
Observational experiments
Explanation, mechanism, hypothesis,
relation
Application
Revision
Assumptions
More
different
assessment
Testing experiments
Yes
Some of the main goals of ISLE philosophy are to help students understand how the body of knowledge is constructed and develop scientific habits of mind.
We call them SCIENTIFIC ABILITIES (in K-12 education they are called “practices”)
What are those?
Scientific abilities
• representing physical processes and ideas
• designing an experimental investigation (three types)
• collecting and analyzing data
• devising and testing a qualitative explanation or a quantitative relation
• modifying an explanation or a relation in light of new data
• evaluating
• communicating
What do our assessments (tests) look like in a course that aims to develop the scientific abilities?
1. You have a loop of wire connected to a galvanometer (shown in the diagram), and a bar magnet.
a. Describe an experiment that will make the galvanometer needle deflect to the right. Include a labeled diagram. The needle deflecting to the right indicates that current is flowing into the port on the right side of the galvanometer.
b. Explain in detail what causes the current to start flowing in that direction.
Paper and Pencil Exam Questions
2. In one of our labs this semester you were asked to determine the elastic potential energy stored in a toy car launcher. You decide to take this one step further and design an experiment to determine the “spring constant” of the launcher. To do this you set the launcher to its second highest setting (which involves pulling the launcher back 12.7cm) and launch the car (mass 60g) three times. Each time you use a stopwatch to record how long it takes the car to travel 50.0 cm down the track. The results are shown in the table.
a. Devise a mathematical method that uses these measurements to determine the spring constant of the launcher. Use this method to obtain an answer. Include the uncertainty in your answer.
b. Describe one assumption you made in your mathematical method. Does this assumption cause your method to overestimate or underestimate the spring constant?
Trial Time
1 0.32 s
2 0.35 s
3 0.30 s
Lab practical exam question
You need to develop a simple version of a projector. The image that it projects must be three times as large as the object. As part of your report you must include a precise and detailed drawing of your projector complete with measurements that someone else could use to build it.
Available equipment: Assortment of convex and concave lenses, meter stick, viewing screen, light source w. crosshairs pattern (the object).
When and how do students develop those?
One of the strategies: The lab is completely integrated and basically
drives the course.In the labs students do initial observations to come up with patterns or models, and then they test and apply them after a discussion in a large room meeting. THEY DO NOT READ THE BOOK BEFORE CLASS!
Students design their own experiments
in every lab!
Design an experiment to find a relation between a voltage across and current through a commercial resistor. Design an experiment to test whether this relation applies to an incandescent light bulb.
Design an experiment to test a hypothesis: interaction of electrically charged objects can be explained by magnetism.
Design two independent experiments to determine the specific heat of the given object. The material of the object is not known.
Use the list of available equipment (xx, xx) to pose your own scientific question. Investigate the question and write a report.
Students design their own experiments
in every lab!
Guided by scientific-abilities focused questions
Self-assess their work and improve it with the help of rubrics
Rubrics for guidelines, assessment and self-assessment
The effects of relevant assumptions are determined correctly but assumptions are not validated.
Needs improvement
(2) The effects
of relevant assumptions are determined and assumptions are validated.
An attempt is made but effects are described vaguely.
No attempt to determine the effects of relevant assumptions.
To evaluate specifically the ways in which the assumptions might affect the result
Adequate
(3)
Not adequate
(1)
Missing
(0)
LEVEL
sub
ABILITY
Basic rubric structure
A student writes relevant things with some minor omissions
(description of what is missing)
Needs improvement
(2)
As perfect as we can expect
(a list of all good stuff)
A student knows that she/he needs to write something but what is written is vague (description of what is missing)
The student does not know that she/he needs to address this issue
Small sub ability
Drawing a free-body diagram
Comparing results of two experiments
Adequate
(3)
Not adequate
(1)
Missing
(0)
LEVEL
ABILITY
What is the smallest setting of a HotWheels car launcher that will allow the car to do loop the loop
without falling?
A part of it is to design an experiment to determine the elastic potential energy stored in the launcher
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Experiment 1: For each notch, shoot car up into the air, measure the distance that it goes in the air until it starts to fall. Then we can find PEg and use it to find PEspring : PEg = PEspring. Ug = mgy
Student written lab report - our data source
We measured mass of the car, the distance it travels into the air (shoot against the wall and mark the wall where the car reaches max)
Us = mgy
We assume that the car is point particle, that it shoots straight up and that we can accurately measure the vertical distance.If we cannot measure accurately our values cannot be accurate.
Student written lab report - our data source
We estimate our measurement of the distance is accurate to +/- 2cm. We estimate that uncertainty from assuming car is a point particle is about +/- 6cm (length of the car). This uncertainty is the largest so we will ignore others. This is a relative uncertainty of 11%.
y mgy
1st notch 0.515m 0.141 J
2nd notch 0.720m 0.198 J
3rd notch 0.945m 0.259 J
4th notch 1.175m 0.322 J
Student written lab report - our data source
Uncertainties: Most of important uncertainties are identified (Adequate).
Evaluation of uncertainty: Random uncertainty is not evaluated. The final result does not incorporate uncertainty. (Inadequate)
No attempt to minimize uncertainty (Missing).
Assessment of student work
Scientific Ability to collect and analyze data;
Rubrics: identify, evaluate, and minimize uncertainty
Study 1: How do students develop
scientific abilities?
Physics for the sciences 193/194 (190 students) ISLE-based with design labs since 2003
Used rubrics to score lab reports (60 x 12 = 720 reports)
Reliability > 90%
Observed students in the labs and created timelines for their behaviors
Ability to identify uncertainties
0% 20% 40% 60% 80% 100%
Lab 8
Lab7
Lab5#2
Lab5#1
Lab4#2
Lab4#1
Lab2 0&1
2&3
HW
Lab2
Lab4
Lab5
Lab7
Lab8
Lab6
Lab9
Lab10
HW
HW
HW
Ability to evaluate uncertainties estimating the largest uncertainty
0% 20% 40% 60% 80% 100%
Lab 8
Lab7
Lab5#2
Lab5#1
Lab4#2
Lab4#1
Lab20&1
2&3
Lab1
Lab2
Lab4
Lab5
Lab7
Lab8
Lab6
Lab9
Lab10
Ability to identify assumptions
Lab3
0% 20% 40% 60% 80% 100%
Lab9
Lab 8
Lab7
Lab5#2
Lab5#1
Lab4#2
Lab4#1
Lab30&1
2&3
Lab1
Lab2
Lab4
Lab5
Lab7
Lab8
Lab6
Lab10
Ability to evaluate assumptions
Lab3
0% 20% 40% 60% 80% 100%
Lab 10
Lab 8
Lab7
Lab5#2
Lab5#1
Lab4#2
Lab4#1 0&1
2&3
Summary of Findings
Time dependence
Content dependence (especially the effects of assumptions!)
Significant improvement
Saturation
Lots of time spent on sense-making and writing!
Study 2: Do students transfer scientific abilities?
Experimental and control groupSame course
Designing a physics experiment
Comparison
Designing a biology experiment
Solving regular exam problems
Week 1-10
Week 12
Week 13
Week 5, 11, 15
Design labs+Rubrics PER based labs
non-design
Experimental group Control group
Students’ activities during semester labs
Design Group
Non-Design Group
30 60 90 120 150 180
MUUDOUMMDMDMM
sense-making 17 min
writing 60 min
procedure 17 min
off-task 5 min
TA’s help 31 min
30 60 90 120 150 180
MPDDAA A M A R MMMDA U D D MROA
AD M
sense-making 44 min
writing 64 min
procedure 20 min
off-task 2 min
TA’s help 16 min
Students’ activities during semester labs
Design Group
Non-Design Group
30 60 90 120 150 180
MUUDOUMMDMDMM
sense-making 17 min
writing 60 min
procedure 17 min
off-task 5 min
TA’s help 31 min
30 60 90 120 150 180
MPDDAA A M A R MMMDA U D D MROA
AD M
sense-making 44 min
writing 64 min
procedure 20 min
off-task 2 min
TA’s help 16 min
Mathematical Model
Mathematical Model
Design
Design
Concept
Revising
Assumptions
Uncertainties
ConceptRevising
Others
Others
0
50
100
150
200
250
300
design non-design
minutes
SM Distribution
y = 40e-0.23x
y = 41e-0.024x
0
10
20
30
40
50
60
Lab1 Lab2 lab3 Lab4 Lab5 Lab6 Lab7 Lab8 Lab9 Lab10
minutes
nondesign design
SM vs Time
0
10
20
30
40
50
60
70
80
90
sense-making
writing proceedure reading TA's help off-task
Time (min)
design
no-design
Time Spent on the lab activities Weeks 1 through 10
Design experiments to determine whether the helium balloon and the air balloon have the same drag coefficients.
Physics transfer task: Investigation of the behavior of the balloon
30 60
Sense-making: 43 min
Writing: 43 min
Procedure: 35 min
Off-task: 0 min
TA’s help: 8 min
90 120 150 180
Reading: 9 min
MinA M UDDDD DMD D MAMU DD MinM MM U U AA
Design Group
DDD MDD MMD MMMM M M
Sense-making; 20 min
TA’s help: 29 minReading: 11 min
30 60 90 120 150 180
Writing: 35 minProcedure: 26 min
Off-task: 0 min
Non-Design Group
0
10
20
30
40
50
60
70
80
sense-making
writing procedure reading TA's help off-task
design
non-design
Time spent on lab activities
Design Non-designp - level of
significance
Total time 162±17min 120±25min 0.0375
Sense-making 52±10min 15±5min 0.0007
Scientific Abilities
0
10
20
30
40
50
60
70
80
"0" "1" "2" "3"
0102030405060708090
100
"0" "1" "2+3"
Ability to identify the assumptions
Ability to evaluate/validate effect of assumptions
Difference is statistically significantChi-square = 67.90, p < 0.001
Identified relevant and significant assumptions
64% of design students13% of non-design students
“0” – missing“1” – inadequate“2” – needs some improvement“3” – adequate
Design
Non-design
Difference is statistically significantChi-square = 53.3 , p < 0.001
Scientific Abilities
0102030405060708090
"0" "1" "2" "3"
Ability to evaluate the uncertainty
0
5
10
15
20
25
30
35
40
"0" "1" "2" "3"
Ability to evaluate the results by independent method
“0” – missing“1” – inadequate“2” – needs some improvement“3” – adequate
Design
Non-design
Difference is statistically significantChi-square = 30.1167, p<0.001
Difference is statistically significantChi-square = 16.36, p < 0.001
Physics understanding
0
10
20
30
40
50
60
70
"0" "1" "2" "3"
Consistency of multiple representations
0
10
20
30
40
50
60
70
80
"0" "1" "2+3"
Free Body DiagramDifference is statistically significant
Chi-square = 17.73, p<0.001
“0” – missing“1” – inadequate“2” – needs some improvement“3” – adequate
Design
Non-design
Difference is statistically significantChi-square = 7.838, p<0.025
2% of design students22% of non-design studentshave score “1” - draw wrong FBD
Biology transfer task
Conduct two experiments to determine transpiration rate using stem cuttings from a single species of plant.
Summary of findings
Increased time on sense making
Professionalism in lab reports
Coordinated representations
Recognized assumptions
Evaluated uncertainties
Results, evaluated by an independent method
What will our students remember when they forget everything?