Introduction to Teaching in the Next Generation Science Standards Classroom

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What is Three-Dimensional Learning?

Many changes have taken place in the teaching of science informed by the work of the Next Generation Science Standards (NGSS). Currently, science learning in the classroom is envisioned as involving students in working and talking together to make sense of phenomena. A phenomenon is anything that happens; it can be as simple as a falling ball or as complex as a hurricane. In a well-designed NGSS curriculum the phenomena introduced are carefully chosen so that the core scientific ideas that are the target for the unit explain how or why the phenomenon occurs. Phenomena are also selected as much as possible to be interesting and relevant to students and/or their community.

In the NGSS classroom, students use three dimensions of science learning as they investigate and make sense of phenomena. These three dimensions are:

• Engaging in Science and Engineering Practices (SEPs)
• Applying Crosscutting Concepts (CCCs) as lenses for questioning
• Learning and applying Disciplinary Core Ideas (DCI’s)

What are the Science and Engineering Practices?

The above list of practices are what scientists and engineers actually do as they do their work. While the practices and the elements of each practice can be listed separately, in real life, scientists and engineers use them in a cycle that calls on each one multiple times. Importantly, the work of scientists often involves more than one practice at the same time.

In the NGSS science classroom, students are invited to engage in learner versions of these same practices to deepen their science learning. Moreover, they are guided in reflecting on how these practices help them understand the world around them, in discussing what their experience tells them about the nature of science or engineering as a discipline and in considering how the science ideas they are learning about were developed.

This figure illustrates that the use of the science practices is a non-linear and often recursive process. This process of sense-making involves using all of these practices, as needed, to get to a satisfactory explanation of a phenomenon.

As the figure shows, in the classroom, in order to construct an explanation of a phenomenon, students begin from their prior knowledge and their initial observations (preliminary investigation) of the phenomenon.

They use these to develop an initial model of the system they observed. The attempt to model raises a lot of questions about what actually happened. Communication with peers about their several models begins the process of refining and revising the initial model.

To test the model they plan and carry out further investigations. Further questions arise as they iteratively investigate to test, then revise and refine their model until it is adequate. The tests of the model require them to analyze and interpret data from their investigations, and often to use mathematics and computational thinking.

Some of the questions will require them to obtain and evaluate information from expert sources, including through short lesson segments in which the teacher introduces an expert’s idea, or through learning resources such as books, websites, video or computer simulations.

Students continue to test and refine their models until the class can reach consensus that they have an adequate model. An adequate model is one that provides a correct prediction for tests made on the system and allows students to construct a model-based explanation of the phenomenon. Thus the model provides an evidence-based element of the reasoning in an argument to support explanation of how or why the phenomenon occurred. When students can communicate their explanation, the reasoning for it, and the way the science ideas they have learned play a role in it, they have reached a satisfactory end to the cycle.

The place where new aspects of a science core idea are learned is shown in the diagram as “obtaining information (about expert knowledge)”—it occurs at the point when students have begun to recognize that their prior ideas need to be augmented, that they need to learn something new, in order to satisfactorily explain what is occurring in the phenomenon.

In science an explanation is more than a description (this is what occurred). It is a claim about how or why it occurred. Such a claim needs to be supported by an argument that describes the mechanism of cause and effect based on a model and the evidence derived from investigations of the system. A model provides a description of the system and how it functions, and is tested and refined until it passes the tests. It is a key bridge supporting the reasoning that relates the evidence gathered to the claimed explanation. The argument answers the question “why do you think that?” and that answer is based on the model and the evidence.

There is not time for every part of the learning to go through this full cycle, particularly as students are also just learning how to engage in each of the practices effectively, so the SISL curriculum is designed to progressively give them responsibility for more and more of the cycle. Early on, the investigations are more pre-planned and controlled by the teacher, but the goal is to allow students more control over what they do as the year progresses.

In engineering projects, the task of explaining a phenomenon is replaced with the task of developing a design which solves a problem. The iterative cycle of engineering design is similar to the iterative cycle of constructing an explanation. In engineering design work, all of the practices are used to develop, test and refine the design plan, rather than the system model and explanation. In engineering, the same set of practices are directed to a different goal and thus are used somewhat differently. A key step that is absent in the science case is that of “defining the problem.” In engineering, defining the problem includes delineating the desired features of and constraints of a successful solution. In designing solutions, engineers use and apply established science knowledge. Similar to the process of constructing a scientific explanation, the process of developing an engineering solution is not linear and has many recursive loops.

One difference between science and engineering is that an engineering problem typically has multiple different solutions that meet the goals and constraints, whereas in science, if two groups of students have different answers, it is important for them to try to resolve any contradictions between them and come up with a class consensus explanation that possibly contains elements of both of the earlier attempts.

What are the Crosscutting Concepts?

Crosscutting concepts are concepts that have application across all sub-areas of science. The ones listed in NGSS are chosen because they form a set of useful lenses for looking at a phenomenon or a problem and trying to figure out what is going on, or what can be done about it. Each lens suggests a perspective from which to ask questions that will help move your understanding or design ideas forward.

The concept or lens of systems and system models is a central part of the pedagogy of NGSS, because we ask students to use this lens every time they meet a new phenomenon or problem. It links directly to the practice of developing and using models that is a key element of what we want students engaged in doing, for reasons explained above.

Once we have defined our system and built an initial model that describes it there are several other lenses that we can use to look at it and decide whether their perspective is helpful as we seek to refine the model and use it to understand what is going on.

• The lens of structure and function leads us to ask whether the shapes and spatial relationships of things are important to think about to understand how the system functions.
• The lens of stability and change leads us to ask questions about under what conditions it is stable and what makes it change.
• The lens of matter and energy: flows, cycles and conservation leads us to examine the system from the perspective of either matter flows and cycles or energy flows and transfers (in both cases including any flows into and out of the system as well as within it) to see what that helps us explain.
• The lens of cause and effect: mechanisms and explanation leads us to ask how our model represents mechanisms in the system by which something causes something else to occur.

Each of these perspectives can be useful in many different science contexts, and so they are all worth thinking about explicitly whenever a problem seems difficult to attack. Often students start asking these questions without explicitly thinking about the lens, because they are directly called to mind by what they are observing, and that is fine too. The point of calling them out explicitly as crosscutting concepts is to help students to notice how generally useful these perspectives are, and thus to call on them even when it is not at first obvious that they are important to understand a system.

The two remaining lenses are a bit different.

• The lens of patterns leads us to ask questions about any patterns that we notice in the system or in its function. This may not help us construct the model initially but it does help us see important features of the phenomenon that must be replicated in or by our model. Questions about the patterns observed are useful in thinking about how to test a model and how to refine it.
• Finally the lens of scale, proportion and quantity leads us to take a quantitative view and ask questions about things we can only describe with numbers (and units).

As with disciplinary core ideas and practices, any explicit teaching about crosscutting concepts should only come at a point when students have begun to use, or reached a point where they need to use, that concept. The best way to learn about them is to reflect on the fact that you have just used them and that they were helpful, rather than to be told ahead of time that you should know them. They are made explicit to support their re-use, not to introduce them the first time.

What are the Disciplinary Core Ideas?

The disciplinary core ideas are what was traditionally thought of and listed as the “content” of science learning, the ideas and understandings that scientists’ have developed through the process of using the practices. In NGSS the focus is on a set of core knowledge across each of the central disciplinary areas of physical sciences (including physics and chemistry), life sciences (including biology and ecology), and Earth and space science. A final area of core ideas is engineering technology and the applications of science, reminding us that there are key concepts students need to learn about the process of engineering design to solve problems. It is important that they become aware of the ways that science is applied across all facets of human endeavor through designed systems to achieve particular human needs or wants (agriculture, medicine, transportation, energy systems to name just a few).

In NGSS students learn what scientists have discovered in a context where they need this knowledge to develop an effective explanation of a phenomenon. At the same time, they are also learning tools for problem solving and figuring things out, that is the science and engineering practices and the crosscutting concepts. All three dimensions are important content of the learning, not just the DCIs.

The goal is that students learn to be able to use the science they learn, and to do that they must practice using it to develop explanations. That is why the standards are expressed as performance expectations that ask students to engage in a specific practice and use a particular crosscutting concept in the context of a particular DCI. However in order to be able to do that, the students need experience of all the practices and the CCCs in many different contexts, so they develop the knowledge and skills to use them well in the context called out by the standard. That is why the SISL curriculum introduces multiple practices and crosscutting concepts in any unit.

The fact that the goal is to be able to figure things out and make sense of phenomena rather than just “knowing” (or rather just memorizing) particular facts and procedures, means that much of the learning occurs in the messy process of making sense of phenomena, and that takes time.

Why Use Three-Dimensional Teaching and Learning? Why Not Just Teach the Facts?

When students use all three dimensions of their science learning to develop models and construct model-based explanations of phenomena they establish their new science knowledge in a different way than if they are taught the same material by conventional reading or lecture, plus scripted experiments or activities designed to demonstrate that it is true. In the NGSS methodology they not only learn the science ideas but they see they are useful for explaining real-world situations and perhaps even more importantly, they acquire greater depth in their understanding of how to use the tools of the practices and crosscutting concepts to address the next problem or phenomenon that they meet. They recognize that they are acquiring “knowledge for use,” not just stuff to remember for the test.

Students will be unlikely to succeed at the types of performances used to demonstrate learning (meet the performance expectations) under NGSS unless they have experienced three-dimensional learning in their classroom. They need this experience to become adept at engaging in the practices and applying the crosscutting concepts and their emerging science knowledge to tackle unfamiliar problems and performance tasks. But beyond any goals of test performance, what the research on science learning suggests is that students who learn science as we are describing here are more likely to retain and use it, are more likely to have a positive view of science as a subject and even of school in general, and are more confident about their ability to learn and understand science.

What Happens in the NGSS Classroom?

The role of the teacher is to facilitate and guide students as they engage in this three-dimensional learning and sense-making about scientific phenomena. This requires the teacher to establish and maintain a classroom culture in which students work together in investigations and model building and struggle together to make sense of the phenomenon they are trying to explain. The teacher sets up their experiences of the phenomena to be studied and the activities that students will need to undertake to explore it, introduces and manages the needed materials, and orchestrates the succession of student work and the time and flow of activity (individual, small group and whole class). The teacher circulates as students work, observes where they are and guides their progress chiefly by asking open-ended questions or eliciting student summaries of where their group is in their thinking. The teacher supports student expression and discussion of ideas, and introduces effective discussion and argumentation strategies by example. The teacher also periodically elicits reflection, moments where students take time to think about what they have been doing and why they were asked or chose to do it. This metacognition is an important element needed for students to understand and internalize the value of the practices, and eventually, the nature of science itself.

New information, whether delivered as a reading, as teacher talk, in a video segment, or using a computer-based simulation, is introduced in short segments. It is offered only once the students have reached the point in their work where they can see the need for this idea to help them improve the models and explanations that they are developing.

Teachers new to this way of learning are often tempted to shortcut the process by telling students the “correct” model or explanation before the students have had time to struggle through to a good model and explanation for themselves. Teachers are particularly anxious about letting students go home with a “wrong” idea in their heads—namely one that is contradicted by the established scientific idea. However, figuring things out, and seeing why the wrong idea is wrong through careful testing and analysis of results, rather than because someone told you it was wrong, is exactly what we want the students to learn to do. They cannot learn that if they are not allowed to work through their own confusions, supported by peer and teacher questioning, at least some of the time. The curriculum is designed to give them some opportunities for that work. In this context, no model is wrong, it is simply not yet adequate and needs some refinement, and the job of the students, with teacher support, is to ask the questions, and in some cases to carry out the investigations, that will reveal the weaknesses and lead to the revisions that improve the model and the model-based explanation.

Classroom Culture of Discourse

Ideally in NGSS classrooms, student ideas are a central goal of the activity. As students develop ideas they will express them hesitantly and partially. It is important that the classroom culture values half-formed ideas no matter what form they are expressed in. Sometimes a diagram or even a gesture is as much part of the way the idea is expressed as are the words. Teachers should model ways to both recognize others’ ideas and respectfully ask questions, helping students clarify or expand upon their ideas by asking follow-up questions or by rephrasing what has been said to check whether they have understood what a student is struggling to express. Students should learn to argue both for or against an idea using models and evidence as the basis for their support or rejection of it. The culture of the room should emphasize a shared goal of coming to a shared understanding, rather than a sorting of students into who is right and who is wrong!

In the stage of idea development it is not important whether the ideas are “correct” or expressed with “correct English” and correct technical terms. An emphasis on correctness kills the flow and stops students from expressing their thinking and discussing it with one another. Encourage students to help others clarify or refine what they have said by asking them good questions, by really trying to understand what the other is thinking. In many classrooms students have not had much experience in listening to one another or expressing the reasoning behind their answers, so it takes time and practice for them to develop these skills just as with any other skill. Structural supports for respectful discourse (for example sentence stems such as “I respectfully disagree because…” or “I think your idea is … Is that what you meant?”) can be useful scaffolds early in the year, but need to be relaxed as the year proceeds.

Assessment for Performance Expectations

The best way to assess a performance expectation is through a performance task. When students are engaged in the practices as they work they are engaged in performance tasks for learning. Performance tasks for assessments can be learning opportunities as well, and in fact a lot of formative assessment in the science classroom can be done by observing the students as they work at the learning tasks. If you want to assign grades then the tasks need to be designed to generate individual scorable products. Tasks should be designed to elicit evidence not only about student knowledge of the disciplinary core idea, but also about students' ability to engage in one or more of the practices and apply the new knowledge for some purpose. At least some tasks should explicitly test student ability to use a crosscutting concept to help achieve the task, but more often these concepts will be in the background of the tasks, possibly used, but not scored.