„The difficulties faced by language instructors in mixed-ability classes are often numerous and invariably lead to frustrations on their part since they are unable to create a productive learning and teaching environment for their students.“
Muneerah S. Al-Subaiei, „Challenges in Mixed Ability Classes and Strategies Utilized by ELI Teachers to Cope with Them“. In: „English Language Teaching“, Vol. 10, No. 6, 2017, S. 183