In readability testing, a passage with 13 difficult words would typically rate at which grade level according to the Gunning FOG Index?

The Gunning FOG Index is a formula used to assess the readability of a passage and estimate the years of formal education required to understand it. The index incorporates two main components: the average number of words per sentence and the percentage of difficult words in the text (typically defined as words with three or more syllables).

When a passage contains 13 difficult words, it indicates a higher level of complexity, which contributes to an increased grade level rating. According to the Gunning FOG Index guidelines, a passage with that number of difficult words would likely classify at an 8th to 9th grade reading level. This suggests that the text is suitable for students who have completed either the 8th or 9th grade, as they are expected to have developed the necessary vocabulary and comprehension skills to navigate such passages.

In contrast, fewer difficult words would typically lower the readability grade, while a greater number would push it higher. The presence of 13 difficult words suggests a certain sophistication in vocabulary that aligns more accurately with the 8th to 9th grade level rather than higher levels, where even more complex and technical language may be expected. This effectively supports the conclusion drawn in selecting the rating of 8th to 9th grade