Science & Engineering Practices:
3. Planning and Carrying Out Investigations
Students should have opportunities to plan and carry out several different kinds of investigations during their K-12 years. At all levels, they should engage in investigations that range from those structured by the teacher--in order to expose an issue or question that they would be unlikely to explore on their own (e.g., measuring specific properties of materials)--to those that emerge from students’ own questions.
(NRC Framework, 2012, p. 61) Scientific investigations may be undertaken to describe a phenomenon, or to test a theory or model for how the world works. The purpose of engineering investigations might be to find out how to fix or improve the functioning of a technological system or to compare different solutions to see which best solves a problem. Whether students are doing science or engineering, it is always important for them to state the goal of an investigation, predict outcomes, and plan a course of action that will provide the best evidence to support their conclusions. Students should design investigations that generate data to provide evidence to support claims they make about phenomena. Data aren’t evidence until used in the process of supporting a claim. Students should use reasoning and scientific ideas, principles, and theories to show why data can be considered evidence. Over time,students are expected to become more systematic and careful in their methods. In laboratory experiments, students are expected to decide which variables should be treated as results or outputs,which should be treated as inputs and intentionally varied from trial to trial, and which should be controlled, or kept the same across trials. In the case of field observations,planning involves deciding how to collect different samples of data under different conditions, even though not all conditions are under the direct control of the investigator.Planning and carrying out investigations may include elements of all of the other practices. Planning and carrying out investigations to answer questions or test solutions to problems in 3–5builds on K–2 experiences and progresses to include investigations that control variables and provide evidence to support explanations or design solutions. - Plan and conduct an investigation collaboratively to produce data to serve as the basis for evidence, using fair tests in which variables are controlled and the number of trials considered. - Evaluate appropriate methods and/or tools for collecting data. - Make observations and/or measurements to produce data to serve as the basis for evidence for an explanation of a phenomenon or test a design solution. - Make predictions about what would happen if a variable changes. - Test two different models of the same proposed object, tool,or process to determine which better meets criteria for success |
An investigation is a systematic way to gather data about the natural world either in the field or in a laboratory setting.
Students: • Design investigations that will produce data that can be used to answer scientific questions. This includes determining the goal of the investigation, developing predictions, and designing procedures. • Identify and analyze experimental variables, controls and certain methods (e.g., how many trials to do). • Conduct investigations to gather data (observations or measurements) using appropriate tools and methods. To get data, scientists may set up a specific controlled situation (like in a laboratory), directly observe phenomena as they occur within the natural world, or may run a computer simulation. The planning stage is a bridge to the questions that originally motivated students’ inquiry. The questions strongly dictate the type of data collected, how precise the data need to be, how much data to collect, and which tools to use. As students plan and conduct investigations, they should be able to do the following: • Collect data, including both quantitative measurements with specific units and qualitative observations. • Assess and minimize uncertainty by repeating and averaging measurements. Apply the concept of variables to design controlled experiments that record the effects of independent variables on dependent variables. Recognize which variables can be fixed or controlled and which cannot. • Represent data using tables, graphs, and charts. • Decide whether a question can be tested by an experiment or requires field observations. • Decide if a computer model will work better than experimentation in the real world (i.e. for phenomena that are too dangerous or too expensive). While school investigations tend to be "tabletop experiments," ideally, students will also conduct investigations that are rooted in real-world data or experiences Engineers plan and carry out investigations to obtain data so they can define the design problem and to test their solutions. For example, before engineers can build a bridge, they must investigate the river and the surrounding landscape to determine potential hazards or construction challenges. Engineers may study the properties of different materials and use computer models to quickly test a variety of possible solutions. Once engineers have created a solution, they perform experiments to test its effectiveness. |