One of the greatest challenges experienced by teachers teaching students who learn English as a foreign or a second language is teaching a class consisting of fast learners and slow learners commonly referred to as mixed-ability classes. The present study investigates challenges experienced by teachers of English language classes encompassing slow learners and fast learners. Data was collected using survey questionnaire and analyzed using Microsoft excel. Results revealed that teachers of English language experience several challenges: mixed-ability class tend to be uncooperative and fast learners get bored easily; challenges in planning for the lesson to teach a mixed-ability class; challenges in creating appropriate work-materials for the mixed-ability class; lack of best approaches to manage mixed-ability class; challenges in getting attention of all learners in a mixed-ability class; and frustration when teaching mixed-ability classroom due to low motivation of weak students.