Source: NRC, 2012, p. 3.
The first dimension included scientific and engineering practices, which were defined as “behaviors that scientists engage in as they investigate and build models and theories about the natural world” (Achieve, n.d.h). The second dimension contained crosscutting concepts, which were defined as concepts that “bridge disciplinary boundaries [and have] explanatory value throughout much of science and engineering” (NRC, 2012, p. 83). (We recommend addressing the crosscutting concepts through vocabulary instruction, as detailed in the book Vocabulary for the New Science Standards [Marzano, Rogers, & Simms, 2015].) The third dimension was composed of disciplinary core ideas (DCIs), which were defined as ideas that “focus K–12 science curriculum, instruction and assessments on the most important aspects of science” (Achieve, n.d.h). Within the third dimension, the NRC identified four scientific disciplines: (1) physical sciences, (2) life sciences, (3) Earth and space sciences, and (4) engineering, technology, and applications of science. Each discipline contained core ideas, which specified areas of knowledge within the discipline with which students should become familiar. Table 1.4 shows how sub-ideas further divide each core idea.
Table 1.4: Core and Sub-Ideas Within the Four Scientific Disciplines
Source: NRC, 2012, pp. 105, 142, 171, 203.
It is important to note that the organizational structure of the NGSS mirrored the order of the core ideas from the framework listed in table 1.4, as content knowledge—disciplinary core ideas—organized the standards rather than either of the other two dimensions (scientific and engineering practices or crosscutting concepts).
Though the NRC (2012) defined the three dimensions separately, it recommended that “in order to facilitate students’ learning, the dimensions … be woven together in standards, curricula, instruction, and assessments” (pp. 29–30). To accomplish such an amalgamation, the NGSS used performance expectations. Each performance expectation in the NGSS was a synthesis of related elements from the three dimensions. As depicted in figure 1.2, each NGSS standard has three sections: (1) a performance expectations section, (2) foundation boxes, and (3) a connections section.
Source: Achieve, 2013b, p. 1.
Figure 1.2: Generic format of an NGSS standard.
The first section contains performance expectations, grade-specific statements that serve as an indication of a student’s proficiency with related knowledge and skills. These statements were considered the leading edge of the NGSS. Some performance expectations have clarification statements, which are specific examples of how the performance expectation manifests in the classroom, or assessment boundaries, which limit the scope of a performance expectation. The three foundation boxes below the performance expectation section represent each of the three dimensions of the framework, with science and engineering practices in the box on the left, disciplinary core ideas in the center box, and crosscutting concepts in the box on the right. The elements within the foundation boxes were eventually “combined to produce the performance expectations (PEs)” found in each standard (Achieve, 2013b, p. 1). Finally, the connections section relates the performance expectations from a given standard to the CCSS, disciplinary core ideas at other grade levels, and other science disciplines at the same grade level.
Figure 1.3 (page 12) shows the first-grade standard related to the core idea of Heredity: Inheritance and Variation of Traits.
Source: Achieve, 2013a, p. 13.
Figure 1.3: Grade 1 NGSS standard for the core idea of Heredity: Inheritance and Variation of Traits.
The standard shown in figure 1.3 contains one performance expectation—“Students who demonstrate understanding can: Make observations to construct an evidence-based account that young plants and animals are like, but not exactly like, their parents” (Achieve, 2013a, p. 13). All the elements in the foundation boxes pertain to the single performance expectation.
Performance expectation codes appeared to the left of each performance expectation in the NGSS. Each code identified the grade level, discipline, core idea, and performance expectation number of the performance expectation associated with it. The grade level identifications were fairly straightforward. A number indicated the corresponding grade level (for example, 1 meant grade 1), and K, MS, and HS aligned to kindergarten, middle school, and high school, respectively.
The following letter combinations related a performance expectation to its specific discipline.
✦ Physical sciences = PS
✦ Life sciences = LS
✦ Earth and space sciences = ESS
✦ Engineering, technology, and applications of science = ETS
Although the NGSS named the fourth discipline engineering, technology, and applications of science, we simply refer to this discipline as engineering.
The number immediately following each discipline abbreviation signaled the core idea within a discipline with which a performance expectation was associated. A list of the core ideas within each discipline can be found in table 1.3 (page 9) or 1.4 (page 10). The final number at the end of a performance expectation code identified which performance expectation within a core idea the code referenced.
Thus, the performance expectation code found in figure 1.3 (1-LS3-1) indicates that the performance expectation is at the first-grade level. The LS3 relates this performance expectation to the core idea of Heredity: Inheritance and Variation of Traits within the discipline of life sciences. The 1 at the end of the performance expectation code identifies this specific performance expectation as the first performance expectation in its core idea of Heredity: Inheritance and Variation of Traits.
Performance expectation codes appeared in each of the foundation