Science A-Z and Text Complexity

Make Science Content Accessible to Students

Science Content

Reading and learning about science can often be a complex and challenging journey for students. To make unfamiliar ideas and associated vocabulary more accessible and less frustrating to students, Science A-Z provides books and other resources at multiple levels of text complexity to support students in accessing the content. These resources can help teachers differentiate instruction to best meet students' needs as they read to learn.

The Science A-Z team evaluates the quantitative and qualitative features of each text to determine its overall complexity. Unit Nonfiction Books and other key reading materials from each science unit within a grade span (K-2, 3-4, and 5-6), are provided at three levels of complexity, indicated by dots on each resource: three green dots for high, two green dots for mid, and one green dot for low. Lexile Measures certified by MetaMetrics are provided for each text to further support decision-making. The following text features are some of the considerations to determine overall text complexity:

  • average words per sentence
  • average sentences per paragraph
  • percentage of unfamiliar vocabulary
  • number and complexity of visual devices (e.g., diagrams, charts, maps)
  • structural elements of nonfiction text (e.g., table of contents, captions, sidebar features, glossary, index)
  • prerequisite prior knowledge
  • concept difficulty

Science topic coverage varies according to standards required by different school districts, states, and countries. Because Science A-Zs resources are provided at multiple levels of text complexity, teachers required to cover standards-based topics can use resources from a higher or lower grade level, as needed, to support students with understanding the language and content of science.

Level Correlation Chart

In order to assign appropriate science texts to students, refer to the chart below for correlations between Science A-Z grade bands and Lexile Measures. Ultimately, teachers should use their professional judgment along with reader and task considerations to determine if an individual text is appropriate for a student.

Grade Band / Science A-Z Level Lexile Measure*
K-2 low one green dot 200L - 440L
K-2 mid two green dots 250L - 540L
K-2 high three green dots 400L - 540L
3-4 low one green dot 500L - 790L
3-4 mid two green dots 550L - 840L
3-4 high three green dots 600L - 890L
5-6 low one green dot 650L - 940L
5-6 mid two green dots 700L - 990L
5-6 high three green dots 800L - 1090L

* Lexile Measures for texts are certified through a partnership with MetaMetrics.