rethinking our goals: what will our students remember when they forget everything? eugenia etkina...

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

QuickTime™ and a decompressor

are needed to see this picture.











A. Van Heuvelen, S. Brahmia, M. Ruibal -Villasenor, M. Gentile, G. Suran



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



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



Are those processes that we need to teach?



Observe





Observe

Hypothesize





Observe



Hypothesize

Predict







Observe



Hypothesize

Predict

Test







Do it again and again until I am satisfied

Children are born physicists who do not give up





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



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.


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


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

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


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


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?

rethinking our goals: what will our students remember when they forget everything? eugenia etkina...

Documents

physics body of knowledge

body of knowledgea process

teaching physics

scientific abilities

physics habits of mind

scientific habits of

physical processes

galvanometer needle