Developing and assessing students’ ability to design experiments in a large enrollment lab class

1. Developing and assessing students’ ability to design experiments in a large enrollment lab class AAPT National Meeting Sacramento, August 2004 Sahana Murthy, Eugenia Etkina, Michael Gentile, Aaron Warren and Alan Van Heuvelen Rutgers University, NJ http://paer.rutgers.edu/scientificabilities Supported in part by NSF Grant DUE #0241078

2. What are design tasks? Investigate new phenomena: Observation experiment Students design experiments to Design an experiment to determine if there is a relationship between pressure and temperature of an unknown substance in a sealed metal sphere. Test a hypothesis: Testing experiment Your friend says that as current flows through a circuit, it is used up by the elements of the circuit. Design an experiment to test this. Solve a practical problem: Application experiment Design experiments to determine the thickness of a strand of your hair using two independent methods, one of which must involve ideas about diffraction.

3. Features of design tasks • Part of ISLE cycle: Observation, testing or application experiment • Divergent thinking-- two independent methods to solve problem • Open ended, ill-defined • Need to perform additional experiments or informed estimates to solve task • Task can involve more than one topic in physics • Qualitative and quantitative experiments

4. Why design tasks: Scientific abilities* • To design a reliable experiment that solves the problem • To choose a productive mathematical procedure • To suggest multiple experiments to accomplish the desired goals • To identify sources of experimental uncertainties • To evaluate effect of experimental uncertainties on data • To make a judgment about the results • To communicate the details of an experimental procedure clearly and completely * Etkina, E., “Developing and assessing scientific abilities in an introductory physics course”, AAPT Announcer, Vol.33, No.4, P.85 (2004).

5. Rubrics: guidelines and assessment

6. Example: P-T relationship Design an experiment to determine if there is a relationship between pressure and temperature of an unknown substance when the volume is kept constant. Equipment: Sealed hollow metal sphere, ice, hot plate, thermometer, pressure gauge. Describe your experimental design. Include how you will measure the pressure and temperature. Draw a labeled diagram of your experimental set-up. Mention what the independent and dependent variables are. List the assumptions you made in your design. Record your observations. Make a table if necessary. Analyze your data and find a best-fit function. What pattern did you find from your observations? Write a verbal description and a mathematical relationship. List experimental uncertainties and how you could minimize them. Evaluate how could these affect your data. Explain how you can use this relationship to predict the value of the lowest temperature possible.

7. Example: DC circuits Your friend says that as current flows through a circuit, it is used up by the elements of the circuit. Design an experiment to test your friend’s hypothesis. Equipment: Battery, wires, bulbs, ammeter. Devise and write an outline of your procedure. Draw a circuit diagram. Use different resistors or light bulbs as your circuit elements. Devise the mathematical procedure you will use to make your prediction. List the assumptions that you made. List experimental uncertainties and how can you minimize them. Evaluate how these could affect the data. Make a prediction about the current at various points in the circuit. Perform experiment and record the results in an appropriate format. Use hypothetico-deducto reasoning with the arguments and evidence for testing your friend’s hypothesis. Is the prediction confirmed? What is your judgment about the hypothesis?

8. Example: Optics Design two independent experiments to determine the width of a strand of your hair. One method must involve ideas of diffraction. Equipment: Laser pointer, meter stick, holder for hair, screen. Devise a procedure and write down an outline. Draw a labeled diagram of your experiment. Write the mathematical procedure you will use. Write how you will measure the physical quantities you need. Perform the experiment. Record your measurements. Calculate the thickness based on your procedure and measurements. What are possible experimental uncertainties? How could you minimize them? Evaluate how these could affect the data. When finished both experiments, compare the two values for the thickness. What are possible reasons for the difference?

9. Implementation • Large enrollment class -- 450 students • Lab class accompanies lecture class • 20 lab sections, 6 TAs • TAs not involved in PER activities • Training -- TAs perform mock design tasks • Collaboration with lab coordinator • One design task per lab • Students perform and write report in 3-hour lab

10. Assessment Authentic Assessment : • Decide goals • Decide assessment • Develop currciculum based on assessment Mueller J, Authentic Assessment Toolbox http://jonathan.mueller.faculty.noctn.edu/toolbox/ Our laboratories: Develop scientific abilities Design tasks with guidelines Formative assessment, Scoring rubrics

11. Student writing samples Week 3 Week 10

12. Research and findings • 35 students in sample • Randomly selected • from 4 sections • Scored student • responses from • week 3 (initial) and • week 10 (final) • Found significant • improvement in • some scientific • abilities

13. Conclusions • Possible to implement and assess open-ended design tasks in large enrollment class • Students’ scientific abilities improved • Assessment rubrics serve as goals for writing new design tasks Further Work • Students use rubrics for self-assessment • Need controlled experiment to test if • guidelines in rubrics caused improvement