Supporting Students in
Constructing Evidence-Based
Scientific Explanations
Joseph Krajcik
Professor of Science Education
Center for Highly Interactive Classrooms,
Curriculum and Computing in Education
The University of Michigan
Substance and Property Explanation Task
Were you just
involved in doing
some form of
inquiry?
Overview of Session
•  Explore the meaning of scientific
explanations
•  Discuss how to support students in
doing challenging tasks such as taking
part in various scientific practices
(explanations)
•  Examine some research
•  Make concluding comments
Scientific Inquiry Practices
•
What are Scientific Inquiry Practices?
•
•
The multiple ways of knowing and doing that
scientists use to study the natural world.
Scientific practices include
•
•
•
Asking questions to guide investigations
Creating, revising and using models
Constructing and revising evidence- based
explanations
•  Using and giving priority to evidence
•  Designing and performing investigation
•  A key aspect of a NRC K – 12 Science Education
Framework
Importance of
Scientific Explanations
•  Core underpinning of science!
Science is explaining
phenomena
•  Key to the science education
standards and the Framework for
K – 12 science education
•  Promote students’ image of
science
•  Enhance students’
understanding of the nature of
science
•  Foster deeper understanding of
important science concepts
Essential Features of
Classroom Inquiry and Their
Variations
Learners
Engage in scientifically oriented
questions
Give priority to evidence in responding
to questions
Formulate explanation from evidence
Connect explanations to scientific
knowledge
Communicate and justify explanations
From the National Science Education Standards
Essential Features of Classroom Inquiry and Their Variations
Essential Feature
Variation
Learner engages in
scientifically oriented
questions
Learner poses a
question
Learner selects among
questions, poses new
questions
Leaner sharpens or
clarifies question
provided by teacher,
materials, or other
sources
Learner engages in
question provided
by teacher,
materials, or other
sources
Learner gives priority
to evidence in
responding to
questions
Learner determines
what constitutes
evidence and collects
it.
Learner directed to
collect certain data
Learner given data and
asked to analyze
Learner given data
and told how to
analyze
Learner formulates
explanation from
evidence
Learner formulates
explanation after
summarizing evidence
Learner guided in
process of formulating
explanation from
evidence
Learner given possible
ways to use evidence
to formulate
explanation
Learner provided
with evidence
Learner connects
explanations to
scientific knowledge
Learner independently
examines other
resources and forms
the links to
explanations
Learner directed
toward areas and
sources of scientific
knowledge
Learner given possible
connections
Learner Communicates
and justifies
explanations
Learner forms
reasonable and logical
arguments to
communicate
explanation
Learner coached in
development of
communications
Learner provided broad Learner given
guidelines to sharpen
steps and
communications
procedures for
communications
More-------------------Amount of Learner Self Direction---------------------------------------------Less
Less------------------------Amount of Direction from Teacher or Material--------------------------------------------More
Adapted from the National Science Education Standards
Explanations in
Classroom Practice
Although important, explanations are
seldom a part of fsclassroom
practice
Project 2061 review of middle school
science materials found that most
materials were unlikely to result in
students developing
understandings of key learning
goals.
Student Difficulties
with Explanations
Evidence
Students have difficulty using appropriate evidence
and connecting evidence to a claim
Students typically discount data if the data
contradicts their current theory
Reasoning
Most explanations include claims with little backing
Scaffolding Scientific Explanation
•  Scaffolds provide students with support for
completing challenging tasks they normally
they could not accomplish only.
•  Provide structure for complex tasks.
•  Making scientific thinking strategies explicit to
students can facilitate their use and
understanding of these strategies.
•  Revealing the underlying and tacit framework
of scientific explanation through scaffolds can
facilitate students’ explanation construction.
What is a scientific explanation?
  A discussion/argument of how or why a phenomenon occurs
and the conditions and consequences of the observed event
Our Framework for a Scientific Explanations
  Claim: a conclusion about a problem. Typically the claim
answers a questions
  Evidence: scientific data that supports the claim
  Appropriate and sufficient evidence
  Reasoning: a justification that shows why the data counts
as evidence to support the claim and includes appropriate
scientific principles
  Consider alternative explanations
  Adapted from Toulmin’s model of argumentation
Identifying Teacher Practices that
Support Students’ Explanation in Science
Researchers
Katherine L. McNeill & Joseph Krajcik
University of Michigan
Instructional Setting
IQWST – Investigating and
question our world
through science and
technology
8 week unit
Middle school science
Develop deep
understanding of science
content and practices.
Learning Goals-Driven
Design
Instructional Setting:
Key Learning Goals
Three Principle Content Learning Goals
•  Substances and properties: Substances are made up of
the same type of atom or molecule throughout and can
be identified and distinguished by their properties.
•  Chemical reaction: Is a process in which two or more
substances interact to form new substances with new
properties. At the atomic level, this means that the
atoms of the old substances rearrange to form the new
substances.
•  Conservation of mass: Mass is neither created nor
destroyed in chemical processes. Atoms simply
rearrange to form new substance.
One Key Scientific Practice
Learning Goal: Explanations
Develop… explanations… using evidence.
(NRC, 1996, A:1D/ 5-8)
Think critically and logically to make the
relationships between evidence and
explanation. (NRC, 1996, A:1E/ 5- 9
Develop…models using evidence. (NRC,
1996, A:1D/ 5-8
Design… a scientific investigation. (NRC,
1996, A:1B/ 5-8)
Content is not enough!
•  Understanding content is inexplicitly linked to
practices! Otherwise, declarative, isolated
ideas.
•  Science is both a body of knowledge and the
process whereby that body of knowledge is
developed. Both elements are essential: one
cannot make progress in science without an
understanding of the other.
•  The learning of science is similar: you can
not learn one without the other.
Instructional Setting: Creating
Learning Performances
What are Learning performances?
  Learning performances define, in cognitive terms, the
designers’ conception for what it means for learners to
“understand” a particular scientific idea
  Learning performances define how the knowledge is
used in reasoning about scientific questions and
phenomena
Know or understand is too vague
Use terms that describe the performance you want students
to learn and be able to do.
  Identify, Define, Analyze and Interpret data, Explain,
Design investigation, …
  Not “know” or “understand”
Instructional Setting:
Learning Performances
Content
Standard
Content Standard
When substances interact to
form new substances, the
elements composing them
combine in new ways. In such
recombinations, the properties
of the new combinations may
be very different from those of
the old (AAAS, 1990, p.47).
Scientific
Practice
Inquiry Standard
Develop…explanations…
using evidence. (NRC,
1996, A: 1/4, 5-8)
Think critically and
logically to make the
relationships between
evidence and explanation.
(NRC, 1996, A: 1/5, 5-8)
Learning
Performance
Learning Performance
LP 12 - Students construct scientific
explanations stating a claim whether a
chemical reaction occurred, evidence in
the form of properties, and reasoning that
a chemical reaction is a process in which
old substances interact to form new
substances with different properties than
the old substances.
Writing Assessments
Learning Performance
Students construct a scientific explanation that includes a claim
about whether two items are the same substance or different
substances, evidence in the form of density, melting point (boiling
point), solubility, color and hardness of the substances, and
reasoning that different substances have different properties.
Assessment Task
Examine the following data table:
Density
Color
Mass
Melting
Point
Liquid 1
0.93 g/cm3
no color
38 g
-98 °C
Liquid 2
0.79 g/cm3
no color
38 g
26 °C
Liquid 3
13.6 g/cm3
silver
21 g
-39 °C
Liquid 4
0.93 g/cm3
no color
16 g
-98 °C
Write a scientific explanation that states whether any of the
liquids are the same substance.
Supports for Explanations
Making Framework Explicit
  Focal Lesson
  Teacher introduces the framework
  Models creating explanations
  Discusses strong and weak examples
  Scaffolds in explanation sheets
Practice
  Students write 10 explanations over the
course of the unit
Feedback
Measures
Students completed identical pre- and
posttest measures that included multiplechoice and open-ended items
Open-ended explanation items
  Substance and properties
  Chemical reactions
Independent raters scored the explanation
items. Inter-rater reliability > 85% for
each component (i.e. claim, evidence,
and reasoning)
Substance and Property Explanation Task
Examine the following data table:
Density
Color
Mass
Melting Point
Liquid 1
0.93 g/cm3
no color
38 g
-98 °C
Liquid 2
0.79 g/cm3
no color
38 g
26 °C
Liquid 3
13.6 g/cm3
silver
21 g
-39 °C
Liquid 4
0.93 g/cm3
no color
16 g
-98 °C
Write a scientific explanation that states whether any of the liquids are the same
substance.
Strong Example for Substance
Explanation (Student A)
Claim = 2
Appropriate Evidence = 3
Inappropriate Evidence = 0
Reasoning = 4
Weak Example for Substance
Explanation (Student B)
Claim = 0
Appropriate Evidence = 0
Inappropriate Evidence = 1
Reasoning = 0
Chemical Reaction Explanation Task
Carlos takes some measurements of two liquids — butanic acid and butanol. Then he
stirs the two liquids together and heats them. After stirring and heating the liquids, they
form two separate layers — layer A and layer B. Carlos uses an eyedropper to get a
sample from each layer and takes some measurements of each sample. Here are his
results:
Measurements
Density
Melting
Point
Mass
Volume
Solubility
in water
Before Butanic acid 0.96 g/cm3
-7.9 ˚C
9.78 g
10.18 cm3
Yes
stirring
&
Butanol
0.81 g/cm3 -89.5 ˚C
8.22 g
10.15 cm3
Yes
heating
After
Layer A
0.87 g/cm3 -91.5 ˚C
1.74 g
2.00 cm3
No
stirring
&
Layer B
1.00 g/cm3
0.0 ˚C
2.00 g
2.00 cm3
Yes
heating
Write a scientific explanation that states whether a chemical reaction occurred when
Carlos stirred and heated butanic acid and butanol.
Intermediate Example for Chemical
Reaction Explanation (Student F )
Claim = 1
Appropriate Evidence = 3
Inappropriate Evidence = 1
Reasoning = 0
Chemical Reaction (Student H)
• Claim = 1
• Appropriate Evidence = 3
• Inappropriate Evidence = 1
• Reasoning = 2
Research Questions
•  Do students achieve learning gains for
scientific explanations?
•  What instructional strategies did teachers
engage in during the focal lesson to support
students’ explanations?
•  Did the teachers’ instructional strategies
measured during the focal lesson predict
student learning of scientific explanations?
Teacher Instructional
Strategies for Explanation
Discuss the Rationale
  Instruction should facilitate students’ understanding of the logic
behind the practice and why the practice is important
Make the Framework Explicit
  Making scientific thinking strategies explicit for students
Model Scientific Explanation
  Modeling the behaviors of a scientist and modeling how to reason
from data
Build Off Students’ Everyday Experiences
  Making connections between students’ everyday discourse and
the science discourse
Videotape for each teacher coded by one of two independent
raters. Interrater reliability was 82%
Participants and Scoring
Site
Urban A
Town B
Urban C
Suburb D
Total
Schools
8
1
1
1
11
Teachers
9
2
1
1
13
Classrooms
32
4
2
3
41
Students
1026
61
51
59
1197
•
Students completed identical pre- and posttest measures. Three
open-ended items were explanations.
•
Independent raters scored the items. Inter-rater reliability was 97%
for claim, 95% for evidence, and 97% for reasoning.
Results: Student Learning
Results: Interaction
Between Rationale and Defining
Figure 4: Interaction Between Rationale and Defining
Posttest Explanation Achievement (Effect Size)
2.5
2
1.5
1
Rationale (1)
Rationale (0)
0.5
0
-0.5
-1
6 (No Definition)
9 (Vague Definition)
12 (Accurate and
Incomplete Definition)
15 (Accurate and
Complete Definition)
Teacher Instructional Strategies:
Discussion of Findings
Discussing the rationale had a positive effect on
student learning
  May help students understand why they are constructing
explanations
Defining scientific explanation depended on whether
the teacher also discussed the rationale
  Discuss rationale
positive impact
  Did not discuss rationale
negative impact
  Just defining the components may be too algorithmic
Development of Scientific Practices:
Physics
6th
7th
8th
Student
Understanding
Chem
Earth
Science
Life
Science
Development of Scientific
Practices: Over Time
Physics
6th
7th
8th
Student
Understanding
Chem
Earth
Science
Life
Science
Museum of Natural History -- NY
Were you involved
in doing some form
of inquiry?
Substance and Property Explanation Task
Concluding Comments
Curriculum materials and teachers can support students in
scientific practices by:
  Discussing the rationale behind the practice
  Making the framework explicit
  Modeling the use of the practice
  Building off everyday experiences
  Providing multiple opportunities to use the scientific
practice
•  Other considerations
  Having students critique examples
  Providing students with feedback
  Developing competence overtime
McNeill, K. L. &
Krajcik, J. (2011).
Supporting grade 5-8
students in
constructing
explanations in
science: The claim,
evidence and
reasoning framework
for talk and writing.
New York, NY:
Pearson Allyn &
Bacon.
Announcement
IQWST is now signed to be published by
Sangari Global Education!
Thanks to many
IQWST Development and Research
Team
Colleagues at University of Michigan,
Northwestern University and the Weizmann
Institute of Science
Kate McNeill at Boston College
Many teachers with whom I work
National Science Foundation

Investigating and Questioning our
World through Science and Technology
(IQWST) (NSF-ESI-0101780 & NSFESI-0439352)
More Information
Contact me
  krajcik@umich.edu
Questions and comments????