A schema is sometimes used to mean an ‘outline model’, or the basic structure of something. In teaching, and in particular reading, we use it because the more you know about something, the easier it is to understand. So if a student is reading something, any prior knowledge that they can bring to the subject can help them predict and fill in any gaps in understanding they may have.
Our prior knowledge of English words and grammar makes this passage readable.
“Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteers be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouth a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.”