Teachers of effective adult literacy instruction need to pay close attention to the difficulty level of texts. The difficulty level of text should be at the zone of proximal development (ZPD) which is not too difficult nor too easy, but at an intermediate level that slightly pushes the learners’ reading proficiency (Graesser, McNamara, & Kulikowich, 2011). We know that working with younger learners that their competence, motivation, and persistence decline dramatically when reading a text that is too difficult (Fulmer & Frijters, 2011). To aid us in selecting appropriate texts, we rely on a computer system called Coh-Metrix (Graesser & McNamara, 2011;  Graesser, McNamara, & Kulikowich, 2011).  Graesser and his colleagues developed Coh-Metrix so that researchers and teachers have a way to scale texts on dozens of aspects of language and discourse. Access the Coh-Metrix tool here. If you want to learn more about Coh-Metrix, follow these links: Basic Overview, Advanced Overview, and Quick Reference Guide.