1. Abstract
Often, students do not learn effectively in science classes. Rather, the
traditional classroom lecture style of teaching generally fails to develop
the critical reasoning skills needed to solve real world problems. It is
especially important that students learn reasoning skills that help them
these problems. Classroom learning traditionally allows the teacher to
present the information to students, followed by the students asking
questions. PRACCIS (Promoting Reasoning and Conceptual Change in
Science), on the other hand, strives to encourage an alternate learning
curriculum that allows students to fully engage in model-based learning.
Model-based learning is focused on creating, defending, and justifying
models based on evidence. Student develop arguments that consider
evidence on both sides and consider the strength of the evidence. In short
PRACCIS aims to have students engage in reasoning practices as similar as
possible to the practices of scientists. In the research reported here, we
report on the effects of PRACCIS on students’ reasoning as exhibited in
essays written on the topic of whether there exist people who are
genetically resistant to HIV.
What is PRACCIS?
PRACCIS stands for Promoting Reasoning and Conceptual Change in
Science. Instead of the traditional method of teaching science topics by
directly showing scientific theories, PRACCIS aims for students to develop
and choose between alternative scientific models given a set of evidence.
The PRACCIS team has created many life science units on topics including
evolution, genetics, cell organelles, and cell processes.
Students participating in this study engaged with the PRACCIS
curriculum for approximately five months. Within this curriculum, we
focus on students work on a three-day lesson within the 4-week genetics
unit. Examining 5 pieces of evidence, they reasoned about whether there
exist humans who are genetically resistant to HIV.
Students’ Reasoning about Evidence in Genetics
Gino Cortes and Megan Yuan supervised by: Clark Chinn and Ron Rinehart
Department of Educational Psychology - Rutgers University, New Brunswick
Methods
The research team gathered data from 20 different classes in one middle
school. We examined data of 3 classes from one teacher. Each class and
teacher were implementing PRACCIS curricula involving using evidence to
develop and/or choose between available scientific models.
The HIV unit – The genetics unit studied is focused on whether or not HIV
resistance exists. Students selected a model at three different times.
Coding for Evidence Quality
We coded to note patterns in student responses by checking the counts and
percentages of each code. Overall evidence quality indicated by student
responses were noted as 1 of 3 general codes.
If a student picked a certain model, we were interested in the justifications
they gave to support their chosen model. The number of students who
acknowledged the alternate model and the number of students who used
body of evidence as justification were also noted.
Results
It is notable to see students use the alternate model and body of evidence to justify a
model after experiencing the PRACCIS module. Our study shows that when supporting
either model 1 or model 2, 11% of students acknowledge the alternate model after
being presented with evidence 1 and 2, while 57% of students acknowledge the
alternate model after being presented with evidence 3 and 4. Furthermore, 9% of
students take into account the multiple evidences and make connections between the
studies (make use of a body of evidence) after being presented with evidence 1 and 2,
while 38% of students make use of a body of evidence after being presented with
evidence 3 and 4, showing a notable increase in those that have taken into account
multiple evidences. Less than 10% of students recognize sample size or scope in
question 9. Other notable codes and their respective counts are listed below.
Conclusion/Future Direction: According to our data there is a notable increase in the
recognition of the alternate model (11% to 57%) and the use of body of evidence (9%
to 38%) from the presentation of evidence 1 and 2 to the presentation of evidence 3
and 4. This increase shows a possible beneficial effect of using a lesson module
similar to that of PRACCIS in teaching scientific theory and argumentation. Students
therefore have an existing concept of using the alternate model and connection of
evidences to strengthen an argument; yet further research is needed to evaluate the
reasoning behind such an increase as it is difficult to definitively attribute this to the
effects of the module-based learning or the increase in evidences presented to
students. Possible implications include using a more open discussion in scientific
debate in classroom (McNeill et al., 2008).
Our results also show that some students have an existing sense of basic statistical
knowledge (less than 10% cited sample size or scope). However, further instruction in
topics such as sample size may be needed to increase the number of students who
acknowledge sample size and scope. Simple restatements of certain evidences e.g.
evidence 4, calls for the need to teach students how to make inferences and elaborate
on answers. This research shows that students engaged in PRACCIS engage overall in
impressive reasoning which appear to be linked to instruction within the PRACCIS
units. Further research by PRACCIS will continue to evaluate the data of different
classes, as well as continue to teach new classes using PRACCIS's science units.
Citations:
Mcneill, Katherine L., and Diane Silva Pimentel. "Scientific Discourse in Three Urban Classrooms: The Role of the Teacher in Engaging High School Students in
Argumentation." Science Education (2009): N/a. Print.
Category Code Example
Large sample size lgsp “There are a lot of patients in this study”
Small sample size smsp “They didn’t look at very many patients”
Small scope smsc “It’s only a small clinic. They should have looked at better
kinds of clinics and hospitals”
Large scope lgsc “They looked at a lot of different kinds of patients”
Model restate mres They simply restate the model as if it was evidence.
Evidence restate eres They simply restate an element of several elements of the
evidence.
Accurate test at The test procedure results in very few errors.
Body of evidence y(# of evidences that
connect)
“There is genetic resistance for cats and monkeys so there is
resistance for humans.”
Authority auth “The nurse clearly shows resistance doesn't exist since she is
a medical professional”
Animals similar to humans ash Animals/FIV similar to humans/HIV
Animals not humans anh Animals/FIV not similar to humans/HIV
other other Significant arguments not captured by any other codes
Category Abbrev. Example
Positive p “This evidence is good because..”
Negative n “This evidence is bad because…”
Unsure u “I’m not sure if this evidence is good or bad..”
Category Code Count %
Model 1 m1 27 48%
Model 2 m2 29 52%
Any citation of evidence 1 e1 39 70%
Any citation of evidence 2 e2 43 77%
Evidence restatement eres 10 6%
Animals similar to humans ash 17 30%
Animals not humans anh 13 23%
Authority auth 13 23%
*Large sample size lgsp 3 5%
*Small sample size smsp 2 3.5%
*Large scope lgsc 0 0%
*Small scope smsc 1 1%
*Alternate model m1 or m2 6 11%
*Alternate model (question 15) m1 or m2 32 57%
*Body of evidence y12 5 9%
*Body of evidence (question 15) y(123 and/or4) 21 38%
Combination Codes % (out of total) % (out of those who supported or found irrelevant)
If evidence 1 supports model 2, then
animals are similar to humans
15 27% 15/22 = 68%
If evidence 2 supports model 1, then
authority is the reason.
7 13% 7/25 = 28%
If evidence 1 is irrelevant to model 1,
then animals are not like humans.
9 9% 9/9 = 100%
This material is based in part upon work supported by the National Science Foundation under Grant No. 0529582. Any opinions, findings, and
conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National
Science Foundation.
PRACCIS Coding Scheme: The PRACCIS team Identified 13
justifications for students’ analysis of quality of evidence. There
were a total of 56 students’ work in this scheme.
Use of Evidence by Students
Model 1 or 2 with no evidence support.
Model 1 or 2 because 1 or more pieces of evidence.
Students provide an argument for the relationship of one or more pieces of evidence to the models.
Both good pieces of evidence (1 and 2) are used and argumentations are provided.
All 3 pieces of evidence (good + bad) are explained and related to the chosen model.
Student explicitly discusses evidence quality.
Students use prior knowledge instead of providing evidence.
Acknowledgements: We would like to thank Alissa Bang, Amanda Corigliano, Paige Frenkle, Ravit Golan-Duncan, Randi Zimmerman,
and the rest of the PRACCIS team for their contributions. We would especially like to thank our advisors, Clark Chinn
and Ron Rinehart, for their yearlong, dedicated effort in guiding our research project.
They picked a model
before they have seen any
evidence, after they have
seen evidence #1 and #2
(question 9), and for a
third time after evidence
#3 and #4 (question 15).
Selecting models several
times allowed PRACCIS to
note changes in reasoning
as their evidence base
grows. Changes in
opinions of whether
genetic resistance existed
were noted in our coding
schemes.