The reading levellers on this series are Barbara Boate and Deborah Kekewich. These experienced educators level the reading passages independently at first, and then meet to discuss and reach a consensus.
Below is a list of the scales* they choose from:
- Automated Readability Index
- Bormuth Readability Index
- Coleman-Liau Index
- Flesch-Kincaid Grade Level
- Flesch Reading Ease
- The Literacy Continuum
- Fry Graph
- Gunning Fog Index
- Lexile Density
- Lexile Score
- Linsear Write Readability Formula
- New Dale-Chall Readability Formula
- Powers-Sumner-Kearl Readability Formula
- SMOG Index
- Spache Readability Formula
*Not all scales are used for each reading passage. Additionally, not all scales used may be listed here.
There are many factors that go into defining a grade level, and Barbara and Deb do not rely solely on these scales. They also consider
- Words— familiarity, frequency, syllable count, transitional words, word choice, context, parts of speech
- Sentence length and complexity
- Text and print features
- Genre, content, and support from illustrations, charts, and photos, etc.
Some passages were levelled multiple times to achieve an accurate reading level.