The number of words per sentence can be a measure of sentence difficulty. Sentences written for beginning readers usually contain a handful of words while sentences written for more proficient readers contain one, two or even three dozen words.
Stacy Arrow hung her jacket on a hook. (8 words) Next to her Jiwon took off her coat. (8 words) Stacy pointed to a sweater on the floor. (8 words) “Whose is that?” (3 words) “No one’s.” (2 words) Jiwon shook her head. (4 words) “It’s been here all year.” (5 words)
• Now compare that novel for beginning readers to a novel for more advanced readers, Harry Potter and the Deathly Hallows. Here are its first paragraph of two sentences:
The two men appeared out of nowhere, a few yards apart in the narrow, moonlit lane. (16 words) For a second they stood quite still, wands directed at each other’s chests; then, recognizing each other, they stowed their wands beneath their cloaks and started walking briskly in the same direction. (32 words)
The type of sentence (simple, compound or complex) can be another measure of reading difficulty.
• In the Spectacular Stone Soup selection, each sentence is a simple sentence with one subject and one verb. Some of the sentences have a prepositional phrase; some have adjectives; some have pronouns, but because of the short length of the sentences and the way each sentence limits itself to one idea, comprehension is easy.
• In the Harry Potter selection, the first sentence is a simple sentence but there are two prepositional phrases and an adverb phrase. The second sentence is a complicated compound sentence. Its first clause begins with a prepositional phrase followed by a subject, verb and two adverbs, followed by a noun phrase and a prepositional phrase. Its second clause (after the semicolon) begins with a participle phrase and a subject, but then begins one predicate with a verb, direct object and prepositional phrase and then begins another predicate with a verb, gerund, adverb and prepositional phrase. Each sentence contains more than one idea.
Word order can be a measure of difficulty.
• In Spectacular Stone Soup, all but one sentence begin with a subject followed by a verb, the usual word order in English. The exception is a sentence which begins with an easy prepositional phrase.
• In the Harry Potter selection, the first sentence begins with a subject and a verb. The second sentence begins with a prepositional phrase, but the second clause in that sentence begins with a participle phrase.
Pronoun antecedents can be a measure of difficulty.
• The Spectacular Stone Soup selection uses the word “it” to refer back to the sweater used two sentences earlier. It also uses the word “her” to refer back to each girl, but that pronoun is stated in the same sentence as its noun antecedent.
• The Harry Potter selection in the second sentence uses several pronouns (they, their, other’s) to refer back to the noun (men) used at the beginning of the first sentence. The pronouns are father apart from their noun antecedent.
Parts of speech used can be a measure of difficulty.
• In Spectacular Stone Soup, the words are nouns, verbs, articles, adjectives, adverbs, pronouns and prepositions. Most are one syllable words but a few are two syllables.
• The Harry Potter selection includes the same types of words, but additionally uses a participle used as an adjective and as a gerund. The passage contains a three- and a four-syllable word.
Coupled with word difficulty, sentence difficulty can make reading passages easy or hard to understand. Authors consider their audiences and their reading abilities carefully before deciding how long to make sentences, whether to make sentences quite simple or complicated, whether to use pronouns or to repeat nouns and whether to write sentences in typical subject-verb word order.
As we mature we want more complicated vocabulary and sentence structure to entertain us. In fiction the story comes first, but how much we enjoy the story depends on the crafting of the sentences by the author. In nonfiction, the facts come first, but again, how willing we are to read those facts depends on the skill of the author in using the components of language, including sentence structure.