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Grade LevelSlightly complexModerately complexVery complexExceedingly complex
Grade 3The text consists of simple, straightforward language and sentence structures. The text is likely slightly complex if it meets at least two of the following criteria:

Sentence type: Primarily simple sentences (typically > 60% simple sentences).

Sentence length: Short sentences (typically <12 average words per sentence).

Subordination: Very low use of subordinate clauses (typically <25% of sentences have subordinate clauses).		The text shows a mix of simple and more complex sentences, introducing some variety in structure without being overly demanding. If the text is not slightly complex, then consider if it is moderately complex based on the following ranges:

Sentence type: Balanced mix of sentence types (typically between 40 to 60% simple sentences).

Sentence length: Medium-length sentences (typically between 12 to 16 average words per sentence).

Subordination: Moderate use of subordinate clauses (typically 25 to 45% of sentences have subordinate clauses).		The text features more elaborate sentences with multiple clauses and ideas, requiring more effort from the reader to parse. Consider if a text is very complex based on the following rates:

Sentence type: Most sentences are complex (<40% of sentences are simple sentences).

Sentence length: Longer sentences (typically between 16 to 19 average words per sentence).

Subordination: High use of subordinate clauses (typically >45% of sentences have subordinate clauses).		The text is dense with very long, intricate sentences and a high degree of subordination, making it exceptionally challenging for this grade level. The text is likely exceedingly complex if it meets at least two of the following criteria, including at least one from the structural density group:

Structural density

Subordination: >50% of sentences have subordinate clauses.

Multiple subordination: >12% of sentences have more than one subordinate clause.

Syntactic complexity: >15% of students are compound-complex.

Length

Sentence length: Very long sentence length (typically >19 average words per sentence).

High concentration of very long sentences: >15% of sentences have >=30 words.
Grade 4The text consists of simple, straightforward language and sentence structures. The text is likely slightly complex if it meets at least two of the following criteria:

Sentence type: Primarily simple sentences (typically > 55% simple sentences).

Sentence length: Short to medium sentences (typically <13 average words per sentence).

Subordination: Very low use of subordinate clauses (typically <30% of sentences have subordinate clauses).		The text shows a mix of simple and more complex sentences, introducing some variety in structure without being overly demanding. If the text is not slightly complex, then consider if it is moderately complex based on the following ranges:

Sentence type: Balanced mix of sentence types (typically between 40 to 55% simple sentences).

Sentence length: Medium-length sentences (typically between 13 and 17 average words per sentence).

Subordination: Moderate use of subordinate clauses (typically 30 to 50% of sentences have subordinate clauses).		The text features more elaborate sentences with multiple clauses and ideas, requiring more effort from the reader to parse. Consider if a text is very complex based on the following rates:

Sentence type: Most sentences are complex (<40% of sentences are simple sentences).

Sentence length: Longer sentences (typically between 17 to 22 average words per sentence).

Subordination: High use of subordinate clauses (typically >50% of sentences have subordinate clauses).

Multiple subordination: >8% of sentences have more than one subordinate clause.		The text is dense with very long, intricate sentences and a high degree of subordination, making it exceptionally challenging for this grade level. The text is likely exceedingly complex if it meets at least two of the following criteria, including at least one from the structural density group:

Structural density

Subordination: >60% of sentences have subordinate clauses.

Multiple subordination: >15% of sentences have more than one subordinate clause.

Syntactic complexity: >20% of students are compound-complex.

Length

Sentence length: Very long sentence length (typically >22 average words per sentence).

High concentration of very long sentences: >15% of sentences have >=30 words.
Grades 5-12The text consists of mainly simple sentences. The text is slightly complex if it has at least 50% simple sentences. Exception: If the % of simple sentences is >= 50% AND the % of compound sentences is >= 20%, the text is Moderately Complex.

Important: Slightly Complex texts NEVER have advanced complex sentences — the presence of an advanced complex sentence always leads to a higher level of complexity than Slightly.		The text contains primarily simple and compound sentences, with some complex constructions. These texts can take on any distribution of sentence types as long as there aren’t more than 2 advanced complex sentences and as long as there aren’t so many simple sentences that the text becomes Slightly Complex.

That means Moderately Complex texts may have many simple sentences (although not so many that the text is Slightly Complex), compound sentences, and/or basic complex sentences. It’s also possible for a moderately complex text to contain one or two advanced complex sentences, as long as there aren’t more than 2. If there are more than 2, then the text is either Very or Exceedingly complex.		The text features many complex sentences with several subordinate phrases or clauses and transition words. These texts contain 3 or more advanced complex sentences (unless the percentage of advanced complex sentences is >= 65%, in which case the text becomes Exceedingly Complex).

They may still contain many simple, compound, and basic complex sentences, but a text is not Very Complex unless there are 3 or more advanced complex sentences.		The text consists mainly of complex sentences with several subordinate clauses or phrases and transition words; sentences often contain multiple concepts.

These texts have 65%+ of their sentences being advanced complex sentences.