Krajcik NSTA Blogs: What's So Special About Disciplinary Core Ideas?

[Note: These blog entries originally appeared online in the NSTA Blog from December 12, 2016 - February 22, 2017.]

What’s So Special about Disciplinary Core Ideas?

By Joe Krajcik | Published: December 12, 2016

I still remember the day Helen Quinn asked if she could visit me at the University of Michigan where I was a professor to discuss the Framework for K–12 Science Education (Framework) and possible roles I might play in its development. I was honored that I was being considered to lead the team on coming up with the big ideas (now called disciplinary core ideas, or DCIs) for physical science. What a privilege and huge responsibility to be part of team to decide the key, big ideas that all students need to know and use to make sense of the world (explain and predict phenomena and find solutions to problems). Not only would our work provide the substance for the Framework, it also would provide the foundation for the development of new K-12 science standards—the Next Generation Science Standards (NGSS)—released in 2013. The physical science team was one of four; Life Science, Earth and Space Science, and Engineering, Technology, and Applications of Science were the other three disciplinary areas. It was a daunting task, particularly because each discipline could pick no more than four big ideas! How could chemistry be boiled down to four big ideas, let alone chemistry and physics? Of course, the core ideas are broken down into component ideas, but it is the disciplinary core ideas that provide the structure and coherence. 

From the start of this effort the disciplinary core ideas were going to be different than the science ideas presented in previous standards documents. Don’t get me wrong, the Framework built on important documents such as the Benchmarks for Science Literacy (AAAS, 1993) and the National Science Education Standards (NRC, 1996). These documents have an important place in the development of science education; they helped guide our nation in science education for two decades and still have a powerful influence on what happens in science classrooms. But the vision of Framework, based on what we know about how students learn, was to help learners develop conceptual knowledge of important ideas that could be used throughout life and get richer and deeper with time. The core ideas serve as a conceptual framework that can be further developed, allowing learners to understand critical ideas about the world in which they live. For example, PS 1 Matter and Its Interactions, supports all learners in understanding the structure, properties, and interactions of matter so they can explain important phenomena, such as how there is such diversity of different types of matter (substances) in the world despite there being relatively few types of building blocks (atoms). Of course, a full understanding of this question and explanation of these phenomena also overlap with PS 2: Motion and Stability: Forces and Interactions and PS 3:  Energy.  Another example is the Life Science Core Idea LS 1, From Molecules to Organisms: Structure and Process, that provides students with the knowledge to explore questions related to how organisms live, grow, respond to their environment, and reproduce. A deep conceptual understanding of this core idea and its components, allows learners to understand where the energy and matter come from to help us grow. A full understanding of the phenomena, however, also requires understanding of PS 1: Matter and Its Interactions and PS 3: Energy.

This blog and those that follow will provide some reflections about the DCIs, but before I go further I have to acknowledge the important role of all three dimensions in making sense of phenomena. Yes, DCIs are critical, but to make sense of phenomena and find solutions to problems, all three dimensions play a critical role.  Science and engineering practices (SEPs), disciplinary core ideas, and crosscutting concepts (CCCs) work together to support students in making sense of phenomena or designing solutions. You cannot learn the ideas of science in isolation from the doing and you cannot learn the practices of science in isolation from the content of science. To develop deep, usable understanding of the DCIs, it is necessary for a learner to use SEPs and CCCs. The basic premise of the Framework is that one cannot learn one without learning the other. The three dimensions work together to help students make sense of phenomena or design solutions to problems, and as students make sense of phenomena they develop deeper, more usable understanding of the dimensions. It basically boils down to “doing science,” or “doing engineering.” Convincing evidence exists that understanding DCIs will only result when core ideas are integrated with SEPs and CCCs, and understanding SEPs will only result when integrated with DCIs and CCCs (NRC, 2007). 

In this blog series, I’m going to explore the DCIs in more depth, including the ideas that DCIs serve as conceptual tools, that they provide explanations for phenomena, and that they develop across time. The first of these follows below and the other two ideas will follow in my next two blogs.

Disciplinary Core Ideas Serve as Conceptual Tools

I’m frequently asked how DCIs differ from science concepts. Energy is energy? Evolution is evolution? Is there a difference in how the Framework presents them and how they were treated in the past? I’ve already mentioned how the DCIs form a conceptual framework; now let’s dig a bit deeper into that idea.

By their very structure, core ideas are different than how standards were previously structured. Each core idea is a conceptual whole that can guide student thinking, but they also link to other core ideas to form even deeper and more meaningful understandings that students can use to make sense of the world.

DCIs support a new vision for science education that moves classroom teaching away from focusing on numerous disconnected science concepts that students memorize, to learning environments where students develop connected understanding of a few powerful ideas that they can use along with SEPs and CCCs to make sense of real-world phenomena or design solutions to problems. The Framework focuses on a limited number of DCIs that students can use to describe and predict phenomena that they experience in their lives. In all, there are 13 DCIs:  4 from Physical Science, 4 from Life Science, 3 from Earth and Space Science, and 2 from Engineering, Technology, and Applications of Science.  The list of DCI’s follows. Click here to explore subcomponents.

LS: Life Science

LS1: From Molecules to Organisms: Structures and Processes

LS2: Ecosystems: Interactions, Energy, and Dynamics

LS3: Heredity: Inheritance and Variation of Traits

LS4: Biological Evolution: Unity and Diversity

ESS: Earth and Space Science

ESS1: Earth’s Place in the Universe

ESS2: Earth’s Systems

ESS3: Earth and Human Activity

PS: Physical Science

PS1: Matter and Its Interactions

PS2: Motion and Stability: Forces and Interactions

PS3: Energy

PS4: Waves and Their Applications in Technologies for Information Transfer

ETS: Engineering, Technology and the Application of Science

ETS1: Engineering Design

I like to think of disciplinary core ideas as conceptual tools that learners can use to make sense of phenomena or solve problems. They are conceptual tools because learners can access them when needed to make sense of a situation. Moreover, they are conceptual tools because as a learner uses them to explore and explain phenomena and solve problems throughout their lives, they learn more about these core ideas and they become more deeply connected to other ideas. 

My next blog will explore how DCIs provide explanations for a variety of phenomena.


What’s So Special about Disciplinary Core Ideas (Part 2)

By Joe Krajcik | Published: January 27, 2017

DCIs provide explanations for a variety of phenomena

Last month I talked about how disciplinary core ideas (DCIs) form a conceptual framework. Now, I’d like to explore the idea that DCIs provide explanations for a variety of phenomena. Phenomena are reoccurring events that occur in the world. That an object falls to the lower point is a phenomenon. This is an everyday occurrence. Phenomena do not need to be phenomenal but they could be.  Babies are born all the time. Birth is a phenomenon, but it is also phenomenal.

Disciplinary core ideas are central to the disciplines of science, provide explanations of phenomena, and are the building blocks for learning within and across disciplines (Stevens, Sutherland, & Krajcik, 2009). In many respects, DCIs are conceptual tools that empower learners to make sense of the world around them. As students use these conceptual tools, the ideas become more connected. While disciplinary core ideas are essential in explaining phenomena within a discipline, they are also essential in explaining phenomena across disciplines. Take for instance the idea of energy. Students can certainly use the idea of energy transfer to track the energy changes when various objects collide with one another. Yet, the concept of energy transfer is also critical in understanding photosynthesis and respiration. By focusing on a few powerful ideas, students learn the connections between ideas so that they can apply their understanding to explain situations that they have not yet encountered.  I often refer to this type of connected knowledge as integrated understanding (Fortus & Krajcik, 2011). Supporting students in developing integrated understanding is critical as it allows learners to solve real-world problems, make sense of phenomena, and learn more.  Perhaps the idea of learning more is one of most critical aspects—as we use the core ideas (along with practices and crosscutting concepts) the core ideas become richer and more connected. 

If you think of a discipline in which you have the most expertise, you can imagine the disciplinary core ideas for that area as they form the network of understanding that allow you to explain phenomena. Close your eyes and think of an important phenomenon in your field. What ideas and what connections among those ideas do you see that explain that phenomenon? The ideas that you see and connections among them are likely core ideas.  For example, individuals who have a background in chemistry might think of reacting various substances to form a new substance with different properties (phenomena) and ideas related to the particle nature of matter and energy (DCIs) to make sense of it. Individuals with backgrounds in physics might think of why a person gets a shock after walking on a rug and then touching a metal door knob (phenomena) and use ideas related to electrical interactions (DCIs) to makes sense of the experience; those with backgrounds in biology might think of the diversity of life that exists on earth (phenomena) and ideas related to natural selection (DCIs) to explain them. Individuals with a background in earth science might envision how earth structures are formed (phenomena) and ideas related to plate tectonics (DCIs) to help explain those structures.

Core ideas are powerful because they are central to the disciplines of science, provide explanations of phenomena, and are the building blocks for learning new ideas both within a discipline and across disciplines (Stevens, Sutherland, & Krajcik, 2009). For example, electrical interactions (PS2) that occur at the molecular level can explain a variety of phenomena. One phenomenon the DCI helps explain is why water boils at the high temperature of 100O C, yet carbon dioxide boils at – 56 O C.  Interestingly, carbon dioxide is a much more massive molecule (44 g/mole) than water (18 gram/mole). What causes water to stick together so much more than CO2? Based on its mass, one might suspect that water should boil at a much lower temperature than carbon dioxide. Using the ideas from the DCI can explain this rather strange case. Because of the strong electrical interactions that exist between water molecules and the relative weak electrical interactions that exist among carbon dioxide molecules, water boils at a much higher temperature. The strong electrical interactions that form among water molecules help to explain other diverse phenomena such as why so much energy is given off in a hurricane (i.e., gaseous water condensing to liquid water) and why proteins fold together the way they do. Explaining a diversity of phenomena is what makes DCIs so powerful.

Let’s take a look at another powerful DCI; gene and environmental interactions. Often students believe that genes alone determine our physical characteristics. While it is true that our genes help determine who we are, the environment also plays an important role. For example, an individual might be prone to type 2 diabetes, but diet and exercise can certainly control the onset of this disease. Bottom line—the environment can do a lot to shape who and what we become. In Disciplinary Core Ideas:  Reshaping Teaching and Learning (Duncan, Krajcik and Ravit, 2016) various chapters expand on the meaning of the disciplinary core ideas and their components.

In the next blog, I’ll explore how DCI’s develop over time.


What’s So Special About Disciplinary Core Ideas? (Part 3)

By Joe Krajcik | Published: February 22, 2017

DCIs Develop Across Time

The first two blogs in my series on disciplinary core ideas (DCIs) focused on how DCIs form a conceptual framework and that DCIs provide explanations for a variety of phenomena. In this final blog I’d like to focus on an important idea reflected in A Framework for K–12 Science Education (Framework) that DCIs are not stand-alone, individual facts that students come to “know” as the result of one lesson or across one grade. Rather, DCIs develop in ways that become progressively more sophisticated as students use those ideas to make sense of new phenomena or problems within and across the grade levels. What is meant by more sophisticated? It means that students’ explanations become deeper and broader allowing them to explain more fully the causes and consequences of a wider array of related phenomena. Sophistication also means that DCIs become integrated with more ideas and experiences. Sophistication is not acquiring more ideas and more details; rather, it is about making connections to ideas and experiences. As ideas get more sophisticated, students come to understand the cause and effect mechanisms that underlie a range of phenomena.

Research from the learning sciences and science education has shown that in order for knowledge to be useful, students need to learn ideas in greater depth and across time.  The DCIs are introduced to students in early grades and develop throughout the K–12 years and beyond. As such, core ideas form a strong foundation to promote continual learning throughout one’s life. Building ideas across time supports learners in developing deeper and more meaningful and sophisticated understandings by forming connections among ideas. These connections will allow learners to apply the understandings to new and novel situations.

For most science educators, taking a developmental approach to teaching science is new.  As teachers and curriculum designers, we need to carefully link new learning and experiences to what students have previously learned, allowing the ideas to become more sophisticated over time. The idea of building on previous ideas is one of the most solid ideas in learning; unfortunately, in the past we’ve seldom given it the attention it deserves. For example, some textbooks present ideas about the water cycle that are dependent on understanding that matter is made of particles, without providing the help students need to develop this idea. The Framework emphasizes the importance of taking a developmental perspective focused on developing ideas over time and building on students’ prior knowledge and experiences.

A developmental perspective requires us, as teachers and curriculum designers, to build and link to students’ current understanding to form richer and more connected ideas over time (NRC 2007). Disciplinary core ideas should develop from elementary through high school. Each year the ideas become more sophisticated, allowing students to provide more complete explanations of phenomena as well as explain more phenomena. 

A developmental perspective guides students’ knowledge toward a more sophisticated and integrated understanding of the scientific idea. For example, if by the end of 5th grade we can help students know and apply the idea that forces acting on an object can cause changes in the object’s speed or direction, we can help learners in later grades develop deeper ideas of forces, including those at the intermolecular level. Similarly, helping 3rd-grade students understand that changes in the environment will cause some organisms to survive and reproduce, others to move to a new location, and others to die off, can lead to deeper understanding of natural selection and evolution in middle school and high school. The grade band endpoints in the Framework show this progression of ideas across time. In Disciplinary Core Ideas:  Reshaping Teaching and Learning (Duncan, Krajcik, & Ravit 2016) various chapters on the DCIs discuss how they develop across time. Examples of how teachers can support student learning at various steps is also presented and discussed.

The developmental perspective also stresses that teaching more content, devoid from the use and application of those ideas, does not allow students to explain or reason about phenomena. Students can memorize science principles, but not really understand them. It helps to reflect back on our own experiences. I remember being able to solve the problems in my college physics class, but I didn’t understand the ideas behind what I was doing or how to apply those ideas to the world in which I lived.

It is critical to realize that growth in understanding is not developmentally inevitable, but depends on what we do in our teaching to provide key learning experiences that help students develop the ideas to become more sophisticated. Reaching the various endpoints depends on the instruction the student receives and how understanding is assessed. Disciplinary Core Ideas:  Reshaping Teaching and Learning (Duncan, Krajcik & Ravit 2016) presents some ideas to move students from one level to another, but development of coherent curriculum materials that build understanding across time is needed.

Concluding Thoughts

Deep, meaningful understanding of disciplinary core ideas are essential to predict and explain phenomena, but DCIs serve as only one dimension in developing this useable knowledge. Science and engineering practices, disciplinary core ideas, and crosscutting concepts work together to support students in making sense of phenomena or designing solutions. Rather than “learning” numerous disconnected ideas, the Framework focuses on helping learners develop a useable understanding of fewer, powerful ideas that develop across K–12-science curriculum and can form conceptual tools that learners can use to make sense of the world. Classroom instruction and curriculum materials will need to support students in reaching these important ideas. As such, curriculum materials and instruction focus on making sense of phenomena using the DCIs, scientific and engineering practices, and core ideas. 

It is also important to realize that DCIs are for all students in our nation. All learners need to develop a sophisticated understanding of DCIs so that they can be used along with science and engineering practices and crosscutting concepts to make sense of the world. Developing useable knowledge will help ensure that we have a sustainable and free world in which to live. If given the chance I might tweak some of the physical science core ideas; but, I am convinced that the full spectrum of DCIs, along with the science and engineering practices, are good guides for our teaching and learning.

I would love to hear from you about the ideas in this blog, your ideas, questions, and feedback. Tweet me at @krajcikjoe or email me  If you want to learn more about the disciplinary core ideas take a look at our new book, Disciplinary Core Ideas:  Reshaping Teaching and Learning, edited by Ravit Duncan, Joe Krajcik, and Ann Rivet, just published by NSTA Press.



American Association for the Advancement of Science (1993). Benchmarks for science literacy. New  York: Oxford University Press.

Duncan, R., J. Krajcik, and A. Ravit eds. 2016. Disciplinary Core Ideas:  Reshaping Teaching and Learning.  Arlington, VA: National Science Teachers Association Press.

Fortus, D. and J. Krajcik. 2011. Curriculum Coherence and Learning Progressions in The International Handbook of Research in Science Education (second edition) Fraser, B. J., K. G. Tobin, and C. J. McRobbie, eds. Dordrecht: Springer.

National Research Council (NRC). 2012. A framework for K–12 science education: Practices, crosscutting concepts, and core ideas. Washington DC: National Academies Press.

NGSS Lead States. 2013. Next generation science standards: For states, by states. Washington, DC; National Academies Press.

Stevens, S., L. Sutherland, and J. S. Krajcik. 2009. The Big Ideas of Nanoscale Science and Engineering. Arlington, VA: National Science Teachers Association Press.


Joe Krajcik

Editor’s note: This blog is the last in a series of three by Joe Krajcik that explore the NGSS disciplinary core ideas. 

Joe Krajcik ( is a professor of science education at Michigan State University and director of the Institute for Collaborative Research for Education, Assessment, and Teaching Environment for Science, Technology and Engineering and Mathematics (CREATE for STEM). He served as Design Team Lead for both the Framework and the NGSS.