Claim, Evidence & Reasoning (CER)

Every science teacher understands the value of students being able to explain phenomena, not simply to define vocabulary words or to answer questions that require them to show what they have memorized. But teaching students to construct explanations is challenging.

IQWST® makes the process easier by supporting teachers and students with a systematic approach that includes the now well-known CER framework. The framework divides explanations into three logical, manageable, and teachable components for middle school students: Claim, Evidence, and Reasoning.

We developed the CER framework alongside teachers who were frustrated by their students’ responses to oral and written questions—typically responding in such brief ways that teachers could not adequately assess their students’ understanding. The CER framework was born and developed in IQWST as a result of teachers’ desire to better support their students as scientific thinkers and writers.

To begin, students must be asked questions that require them to think deeply about what they have observed, read, and experienced and to integrate that information as they explain the how or why of phenomena for a specific purpose and audience. Although an explanation must function as a whole, teachers often find it easier to teach the components separately and explicitly.


A claim is a statement of a student’s understanding of a phenomenon or about the results of an investigation; it answers the original question by expressing what he or she is trying to help an audience understand and believe. In practice, teachers often teach that a claim cannot begin with “yes" or “no," and is typically the first sentence of an explanation.

Although a claim does not need to be the first sentence in an explanation, it is helpful for students to learn to construct explanations with specific guidelines that can be varied later. The claim is typically the part of an explanation that students find easiest to include and to identify as they critique others’ explanations. Claims may be made about data that students have been given or that they have gathered themselves. If an investigation has independent and dependent variables, the claim describes the relationship between them. The quality of an explanation is largely dependent on a good question to begin with, so consider first the question. After an investigation, have students return to that question, and their response, in a sentence, is typically a claim.


While data can refer to all the observations that students have collected or analyzed, data become evidence when used to support a claim. A claim is convincing to someone else only when there is strong evidence to support it.

The evidence for explanations can come from investigations students conduct, from observations they make, or from reports of empirical research others have done. In complex situations, more than one claim might be made about a single data set thus having accurate, appropriate, and sufficient evidence is what makes a claim convincing. The idea that multiple claims might be made using the same data develops across the IQWST curriculum as the inquiry activities become more complex, and students’ options for research questions (and resulting claims and evidence) become increasingly open ended. One challenge of the evidence component is that students assume they do not need to describe the data because their teacher and classmates already know what happened! Thus, helping students to decide which data to choose and how to present those data as evidence is a key step in the process of learning to construct an explanation. Significant time must be devoted to helping students understand what counts as good evidence in science, drawn from qualitative and/or quantitative data, and what it means for evidence to be both appropriate and sufficient.


Reasoning is the most challenging for both students and teachers. Reasoning illustrates why particular evidence is the correct evidence to use in support of a particular claim. Reasoning typically includes describing the scientific knowledge or theory, or what IQWST refers to as the Scientific Principle, that applies to a particular claim and evidence. The principles are not given to students, but are “figured out” through their own investigations and in the context of whole-class discussions.

Reasoning requires students to make explicit the steps of their thinking, showing the logic that leads from the evidence to the claim. Critiquing examples of explanations helps students recognize the components and the need for them. They quickly learn to determine what is missing or inadequately expressed—and because they find this easier than constructing their own explanations, it is often a good starting point. Sharing an anonymous example from 3rd period with students from 1st period enables students to learn what to look for without feeling criticized early in the learning process. IQWST provides systematic scaffolding to guide students in constructing explanations of scientific phenomena and to support teachers in facilitating this process. Using evidence and reasoning to construct explanations is one of the most important practices students can learn, with application beyond science class to high school, college, career, and citizenship readiness in all areas!


College Readiness Results After IQWST® Implementation

IQWST Data Chart

Student Data from a School in Oregon on PS2: Energy

Description of data:

100% of students (from 2 classes) demonstrated growth in proficiency throughout the course of the unit as demonstrated by pre and post assessment data.*

*73% of students are at or above a proficient level.

*27% are partially proficient at grade level.

*After the unit 0% are below proficient at grade level.

Data labels (proficiency 1-4)

  • A score of (4 Advanced) would indicate that a student exceeds grade level standards by consistently demonstrating an advanced level of understanding and/or the ability to apply their knowledge at a higher level.
  • A score of (3 Proficient) would indicate that a student has independently achieved proficiency in the standards. The student demonstrates mastery of the standards.
  • A score of (2 Partially Proficient) would indicate that a student is developing an understanding of a standards, butstill may be in need of additional instruction and/or support.
  • A score of (1 Below Proficient ) would indicate minimal understanding of a standards. The student shows limited evidence of understanding the standards.


The IQWST® Experience: Using Coherence as a Design Principle for a Middle School Science Curriculum

Sequencing and Supporting Complex Scientific Inquiry Practices in Instructional Materials for Middle School Students

Assessing the role of curriculum coherence in student learning about energy

IQWST® is used as an exemplar throughout the National Research Council's Developing Assessments for the Next Generation Science Standards (2014), which can be accessed online for free (citation below).

National Research Council. (2014). Developing Assessments for the Next Generation Science Standards. Committee on Developing Assessments of Science Proficiency in K-12. Board on Testing and Assessment and Board on Science Education, J.W. Pellegrino, M.R. Wilson, J.A. Koenig, and A.S. Beatty, Editors. Division of Behavioral and Social Sciences and Education. Washington, DC: The National Academies Press.

IQWST® is also used as an exemplar throughout Seeing Students Learn Science: Integrating Assessment and Instruction in the Classroom (2017), which can be accessed online for free (citation below).

  • LS2 (What's Going On Inside of Me?) is used to illustrate one of the most important ideas laid out in chapter 1 – that assessment should be grounded in classroom instruction “because it assesses what students have learned from a series of activities that reflect the multiple dimensions of science learning" (p. 33):
  • IC1 (How Can I Smell Things From a Distance?) is used to illustrates how to use class discussion and, in particular, specific questioning strategies as a means to assess student thinking:

National Academies of Sciences, Engineering, and Medicine. 2017. Seeing Students Learn Science: Integrating Assessment and Instruction in the Classroom. Washington, DC: The National Academies Press. doi: 10.17226/23548.