Each curriculum was reviewed and rated on the 14 criteria for effective, comprehensive curricula. All ratings display a star that follows a four-level scale.
For Criterion 1: Evidence Base for Child Outcomes, the overall rating was based on the strength of the research design and child outcomes.
- The lowest level (no evidence = ) indicates either no studies have evaluated the impact of the curriculum on child outcomes, or studies have found only null or negative child outcomes.
- The next level (minimal evidence = ) indicates minimal child outcomes in descriptive, quasi-experimental, or experimental studies.
- The third level (moderate evidence = ) indicates modest child outcomes in one or more areas in quasi-experimental or experimental studies.
- The highest level (full evidence = ) indicates strong child outcomes across multiple experimental studies.
For criteria 2–14 (and criterion 15 for home-based only), the overall ratings reflected the following progression.
The lowest level (no evidence = ) indicates the curriculum shows no evidence of meeting the criterion.
The next level (minimal evidence = ) indicates the curriculum shows minimal evidence of meeting the criterion. For example, the curriculum may describe the importance of practices related to the criterion (e.g., family engagement, linguistic responsiveness) but provides little guidance or teaching strategies to support children's learning.
The third level (moderate evidence = ) indicates the curriculum shows some evidence of meeting the criterion. For many of the criteria, this rating means that the curriculum provides general guidance on effective practice related to the criterion but lacks specific teaching strategies to support learning embedded throughout the materials.
The highest level (full evidence = ) indicates the curriculum shows full evidence of meeting the criterion. At this level, the curriculum offers specific guidance and teaching strategies related to the criterion embedded throughout the materials.