Scaffolding students

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Scaffolding students experimental work with
scientific abilities rubrics

• Maria Ruibal Villasenor, Sahana Murthy,
• Anna Karelina and Eugenia Etkina
• Rutgers University, New Jersey
• http//paer.rutgers.edu/scientificabilities
• Supported by NSF grant DUE-0241078

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• One of the goals of the Rutgers PAER group is the
  development of a curriculum for the introductory
  physics courses taken by science majors.
  Students acquisition of scientific abilities is
  one of the key aims of this curriculum.
• When conducting any experiment, students carry
  out a series of planning, performing and
  evaluating activities. In order to scaffold
  novices during these tasks and, more importantly,
  to scaffold them in the process of acquirement of
  experimentation related abilities, we provide
  them with rubrics that can be applied to all of
  the laboratory activities. The rubrics, which
  have been developed and validated by our group,
  facilitate the task of establishing clear,
  attainable and meaningful goals and offer
  students a way of self-monitoring their progress.
  

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Rubrics support students in two different ways

• The aim of our rubrics is not only to facilitate
  the learning of some scientific concepts, ideas
  and relationships but, more importantly to teach
  the process and nature of science through the
  students actual practice of the scientific
  inquiry.
• Since we are introducing students to the
  practices of real science, we need to provide
  them with the necessary support that will enable
  them to accomplish unfamiliar, complex tasks and,
  at the same time, learn from the experience. Our
  aim is that the rubrics will scaffold learners in
  the course of their knowledge construction in two
  different ways first, allowing novices to
  complete the task, which without help they would
  not be able to accomplish (since learners will be
  working at many times during the lesson on the
  zone of proximal development) and second, but not
  less important, promoting transfer, that is
  helping students to complete successfully
  similar, or not so similar, tasks in the future.
  In other words we intend that a cognitive
  residual persists and may become active in
  different contexts.

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• During regular lab instruction, students design
  and conduct their own experiments with the
  guidance of prompts and questions specially
  written for each particular lab. They assess
  their work using also the rubrics.
• During practicals, students are not provided with
  those specific prompts therefore they have to
  rely for help only on the rubrics.
• Upon removing the prompts and questions, can
  students perform equally well with the sole
  scaffolding of the rubrics?
• We have analyzed students reports of two
  different application experiments written under
  the two conditions (with and without prompts).
  The students are from three different sections
  taught by different TAs. The number of students
  that worked on each of the sections is
  approximately 22.

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Task A (with prompts)

• Determine the net force on a conical pendulum
• Design two independent experiments to determine
  the net force exerted
• on a conical pendulum by other objects as the bob
  of the pendulum
• moves in a circle at constant speed.
• Hints Let the bob move in a circle of larger
  diameter, say 1m. You could
• analyze the motion using concepts from
  kinematics.
• Equipment A heavy bob at the end of a string, a
  meter stick, a spring
• scale, a stopwatch.
• Include in you report for each experiment
• a) a complete description of your experimental
  design with a labeled
• diagram
• b) a free-body diagram
• c) a procedure that you will use to determine the
  net force
• d) the physical quantities that you will measure
  and quantities that you
• will calculate.
• e) additional assumptions that you made
• f) sources of experimental uncertainty and ways
  to minimize them
• g) perform each experiment and record the data.
  Compare the two
• outcomes and discuss if the difference can be
  explained by your

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Task B (without prompts)

• Part 1 Determine the energy stored in the Hot
  Wheels launcher
• The Hot Wheels car launcher has a plastic block
  that can be pulled back to latch at four
  different positions. As it is pulled back, it
  stretches a rubber band a greater stretch for
  each of the four latching positions. Your task is
  to determine the elastic potential energy stored
  in the launcher in each of these launching
  positions using the generalized work-energy
  principle.
• Equipment Hot Wheels car, Hot Wheels track, Hot
  Wheels launcher, meter stick, two-meter stick,
  ruler, masking tape, timer, scale to measure
  mass.

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Task B (without prompts)

• Part 2 Getting the Hot Wheels car to
  successfully make a loop-the loop
• Your task is to determine the least energy
  launching position so that the car will make it
  around the loop without loosing contact with the
  loop on the FIRST TRY (Do not use a trial and
  error method). If you use the next lower energy
  setting, the car should not make it around the
  loop. You may use the results you obtained from
  the previous experiment.
• Equipment Hot Wheels car, Hot Wheels track,
  Hot Wheels launcher, meter stick, two-meter
  stick, ruler, masking tape, timer, scale to
  measure mass, Hot Wheels loop-the-loop and
  spin-out.

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The scientific abilities considered in this study

• In order to complete satisfactory the tasks
  given to the students in the two instances, they
  have to display proficiency in a series of key
  scientific abilities. For this study, we focused
  our attention on a selection of abilities that
  students, as well as scientists, must have when
  designing and conducting application experiments.
• The criterion for our selection, in addition to
  its relevance, have been that this collection of
  abilities was the one in common needed and
  requested to accomplish the two tasks proposed to
  students.
• The researchers have used for scoring the lab
  reports the same rubrics that the students
  utilize for guidance and self-assessment, and the
  same ones that TAs use for grading the
  experimental work of the students.

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(No Transcript)
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How were scored the reports ?
Find the magnitude of the potential energy stored
in each of the launch positions of the Hot
Wheels Launcher.
SCORE ABILITY 0 1 2 3
To identify assumptions made in the chosen procedure No attempt is made to identify any assumptions. An attempt is made to identify assumptions, but most are missing, described vaguely, or incorrect. Most assumptions are correctly identified All assumptions are correctly identified.
Scoring samples taken from students reports
Car is a point particle... ...we are neglecting
friction... ...we designate zero h at the
beginning of the track. System Earth, track,
launcher, car. SCORE 2
Calculations are correct... ... friction is
negligible... ...measured values are
correct... SCORE 1
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Students performance (All sections)
Average score per student per ability Condition
With prompts 1.83 Without
prompts 1.75
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Students performance (Section I)
Average score per student per ability Condition
With prompts 2.0 Without
prompts 1.9
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Students performance (Section II)
Average score per student per ability Condition
With prompts 2.0 Without
prompts 1.9
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Students performance (Section III)
Average score per student per ability Condition
With prompts 1.44 Without
prompts 1.42
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Difference between scores under the two
conditions(score of the task with prom score
of the task without prompt)
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Statistical differences

• Is there a statistical significant difference
  between the scores of the students under the
  first and second conditions?

z (?x 1 /n 1) (? x 2 / n 2)/ (s 12 / n 1)
( s 22 / n 2 )1/2 At z 0.22, ?z?lt z0.05 (
2.101), clearly the difference between the mean
scores is not significant. The difference
between the two conditions for each of the
sections is as well non significant, since z I
0.51 , z II 0.35 and z III 0.05
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CONCLUSIONS

• This study shows that our rubrics might help as
  a tool for procedural facilitation (the
  investigative steps are explicitly stated). We
  have not found a significant difference between
  the effects of the scaffolding by including
  prompts and questions in the task, and the sole
  scaffolding of the rubrics.
• The rubrics help novices to complete the task,
  which involves complex and unfamiliar scientific
  abilities. Additionally, we believe the rubrics
  also improve the transfer of these abilities.
  These features make the rubrics a helpful tool
  to guide students through their learning .