I'm not sure what's wrong with the paragraph below. Could someone please help me to see the mistakes?

In a study conducted by McLellan & Chua-Wong, (2002) on code switching, teachers revealed that they code switch in order for pupils to understand lesson content. Furthermore, Words and concepts explained in students L1, become more accessible to students than words explained in English. Another reason to code switch is the need to maintain the flow of communication between English teachers and students which saw 85.7% of the respondents who agreed to this.