Observational/historical sciences (such as astronomy, geology and climatology) and experimental sciences (such as physics and chemistry) have fundamentally distinct methodologies (Cleland, 2002). In observational sciences, it is not possible to have an independent variable and a control variable with all other elements held constant. One must make targeted observations of nature as it is and attempt to find patterns and logic within those available data sets. In experimental sciences, one can set up a controlled experiment, frequently in a laboratory setting, which allows the researcher to investigate how changing a single variable affects the other aspects of the system being manipulated.

Both observational and experimental approaches to science are valid methodologies, despite the differences in their manner of data collection and analysis. Yet the educational establishment privileges experimental methods, coursework, and student experiences over observational ones (Gray, 2013). In particular, the NGSS Science Practices privilege approaches to scientific inquiry that align with experimental science methods and leave out observational science methods. An attempt to correct for some of this bias led to the writing of The Nature of Science standards, yet these standards are not readily advertised as part of the NGSS (Achieve, n.d.).

Everyone is familiar with using experiments in the classroom as a form of scientific inquiry, but this does not always work for all sciences. Gray (2013) proposes adding four additional methodologies beyond experiments: retrodiction, abduction, reasoning from analogy, and multiple working hypotheses. These are listed below with example as described by Gray. All of these methods, including experiment, work smoothly within the framework of the NGSS Science and Engineering Practices, despite those practices giving limited examples of non-experiment methods.