Students often struggle with listening because of their pronunciation. Since they mispronounce words, they expect a different pronunciation and cannot recognize words because they are pronounced differently. It is not unusual that they don’t recognize words because the speaker’s pronunciation is different from the one they are used to (usually the teacher’s pronunciation). Students very often prefer one variety of the English language, e.g. British, only because they have had British teachers in English. However, English has many varieties.So, it’s essential that you approach pronunciation and varieties from the first lesson at A1 level.