Everybody knows that prior knowledge is critical in order to comprehend a text (see The Best Resources For Learning About The Importance Of Prior Knowledge (& How To Activate It)).
But how much background knowledge do you actually need?
According to a recent study, How Much Knowledge Is Too Little? When a Lack of Knowledge Becomes a Barrier to Comprehension, 59% is the key amount.
Here’s a summary from an Edutopia email (there’s no way I can link to it):
The upshot: If your students are familiar with less than 59% of the terms related to a topic (which converts to a background score of about 34), they’ll probably struggle to gain further traction.