NGSS: Science and Engineering Practices

The Next Generation Science Standards (NGSS) place “doing science” at the center of instruction. Instead of treating science as a list of facts to memorize, NGSS emphasizes eight Science and Engineering Practices that describe how scientists investigate the natural world and how engineers design solutions to problems. These practices are integrated across life science, physical science, Earth and space science, and engineering, and they are meant to be used repeatedly, in increasingly sophisticated ways, from elementary school through high school.

At their best, the practices make science classrooms feel more like real scientific inquiry and engineering work: students ask questions, build and revise models, analyze data, argue from evidence, and communicate what they have learned. They also create a common language for teachers, curriculum designers, and assessment writers to describe what students should actually do to demonstrate understanding.

What the Science and Engineering Practices Are (and Why They Matter)

NGSS identifies eight interrelated practices:

1. Asking questions (for science) and defining problems (for engineering)
2. Developing and using models
3. Planning and carrying out investigations
4. Analyzing and interpreting data
5. Using mathematics and computational thinking
6. Constructing explanations (for science) and designing solutions (for engineering)
7. Engaging in argument from evidence
8. Obtaining, evaluating, and communicating information

These are not “steps of the scientific method” in a fixed order. Real investigations and design cycles are messy. Students might start with a model, notice that it fails to explain a phenomenon, gather new data, revise the model, and then argue about which explanation is strongest. The practices matter because they help students learn science as a way of thinking. When students can use evidence, reasoning, and models, they are better prepared to apply science in unfamiliar contexts, including real-world decision-making.

Practice 1: Asking Questions and Defining Problems

Scientific inquiry begins with questions that can be investigated. In the classroom, strong questions are specific, testable, and grounded in observations. For example, “What affects how fast a puddle dries?” can lead to investigations involving sunlight, temperature, wind, surface type, and water volume.

Engineering starts with defining a problem. A well-defined problem includes criteria (what the solution must do) and constraints (limits such as materials, time, safety, or cost). For instance, “Design a container that keeps an ice cube from melting for 30 minutes using only cardboard, foil, and tape” sets clear boundaries and invites creative solutions.

Practice 2: Developing and Using Models

Models are simplified representations that help explain or predict phenomena. They can be drawings, physical replicas, diagrams, mathematical relationships, simulations, or conceptual frameworks. Modeling is not about making something “pretty.” It is about capturing key relationships and using them to reason.

A basic example is a particle model of matter to explain why heating a substance can cause expansion. A more advanced example is using a model of energy transfer to predict how insulation changes heat flow. Students should be expected to revise models as new evidence emerges, because model revision is a core part of scientific work.

Practice 3: Planning and Carrying Out Investigations

Investigations are purposeful. Students make decisions about variables, controls, measurement tools, sample size, and procedures to ensure that data will be useful. In early grades, this might look like making careful observations and recording results. In later grades, students should justify why their methods can answer the question and recognize sources of error.

Engineering investigations include testing prototypes. A design is not “done” when it looks good; it is done when it performs against criteria. Testing, redesigning, and retesting are essential for building a functional solution.

Practice 4: Analyzing and Interpreting Data

Data analysis turns raw numbers or observations into meaning. Students should learn how to organize data in tables, represent it in graphs, look for patterns, and identify outliers or inconsistencies. Interpretation involves connecting patterns to scientific ideas, not simply describing what a graph looks like.

For example, if students collect temperature data from sun and shade, analysis might reveal a consistent difference across multiple trials. Interpretation then connects that pattern to energy from sunlight and heat transfer, supporting a broader explanation.

Practice 5: Using Mathematics and Computational Thinking

Math is not an add-on; it is a tool for describing and predicting the world. Students may calculate averages, rates, proportions, or changes over time. Even simple relationships can be powerful, such as recognizing that speed relates distance and time through $v=\frac{d}{t}$.

Computational thinking includes organizing data, using repeated procedures, and employing simulations or algorithms when appropriate. This does not always require advanced coding. It can include using spreadsheets to model relationships or running a digital simulation to explore how changing one variable affects outcomes.

Practice 6: Constructing Explanations and Designing Solutions

In science, students construct explanations that connect evidence to scientific ideas. A strong explanation includes:

• A claim about what is happening
• Evidence from investigations or observations
• Reasoning that shows why the evidence supports the claim using scientific concepts

In engineering, the parallel is designing solutions. Students generate options, select promising designs, build prototypes, test them, and iterate. The focus is on meeting criteria within constraints, and on explaining why a design works.

A key NGSS shift is that explanations and solutions are expected to be evidence-based. Students should be able to say not only what they think, but why the data support it.

Practice 7: Engaging in Argument from Evidence

Argumentation in NGSS is not debate for its own sake. It is the disciplined practice of evaluating competing ideas using evidence and reasoning. Students might compare two explanations for a phenomenon and decide which is better supported by data. They might critique a classmate’s model by pointing out mismatches between the model and observed results.

This practice builds scientific literacy. In the real world, people encounter claims about health, climate, technology, and risk. Learning to weigh evidence and reasoning helps students distinguish between opinion and well-supported conclusions.

Practice 8: Obtaining, Evaluating, and Communicating Information

Scientists and engineers read, write, speak, and use media to share findings. Students should practice summarizing scientific texts, evaluating the credibility of sources, and communicating their own results clearly.

Communication is not limited to lab reports. It includes posters, presentations, graphs, annotated diagrams, and explanations tailored to different audiences. Evaluation is equally important: students learn to ask whether information is backed by evidence, whether methods are described, and whether claims are consistent with data.

How the Practices Work Together in Real Instruction

The power of the NGSS Science and Engineering Practices is in integration. A well-designed learning sequence might look like this:

• Students observe a phenomenon and ask investigable questions.
• They build an initial model to explain what they think is happening.
• They plan and carry out an investigation to test aspects of the model.
• They analyze data, use math to quantify patterns, and revise their model.
• They construct explanations, argue from evidence, and communicate findings.

Engineering tasks naturally weave in as well, especially when students use scientific understanding to design solutions. For example, understanding heat transfer supports designing better insulation. Understanding forces supports designing a stable structure.

Practical Indicators of Strong NGSS Practice Use

Teachers and curriculum teams often ask what these practices look like in everyday classrooms. A few concrete indicators help:

• Students make decisions, not just follow directions. They choose variables, justify methods, and explain trade-offs.
• Models change over time. Revisions are expected and documented, not treated as mistakes.
• Evidence is visible. Data tables, graphs, and references to observations appear in student talk and writing.
• Argumentation is structured. Students critique ideas respectfully and cite evidence, rather than relying on authority or volume.
• Communication has purpose. Students tailor explanations to an audience and use accurate scientific language without sacrificing clarity.

Closing Perspective

NGSS: Science and Engineering Practices offer a coherent vision of science education grounded in authentic work. They prioritize scientific inquiry, modeling, data analysis, and argumentation, not as separate activities, but as mutually reinforcing tools for making sense of the world and solving problems within it. When students repeatedly use these practices across topics and grade levels, they do more than learn science. They learn how to think, test, revise, and communicate like scientists and engineers.