They need a lot of natural listening/ conversation practice. Grammar will be learned indirect as to what "sounds" right over time. But being able to listen to a native speaker and comprehend what they are saying is a huge factor. Have they been learning English since Kindergarten? If so a lot of conversation practice is what is really needed. Role play activities, planning/problem solving activities, games etc. Anything to get them listening.
I have a game I play with my students kind of like 20 questions except I call it the "hot seat" I sit a chair in front of the white board (back of the chair pointed towards the white board) and ask for a volunteer. The student sits in the chair and then I write a word on the board such as Mango, tok tok, taxi, donkey, etc. The student then has to ask questions that can be answered as yes, no, maybe, sometimes or related to.
I always give the basic questions: Can I ride in/on it?(difference especially with motorcycle) Can I eat/drink it? Is it in this room? Is it electronic? Can I visit it? Is it used in my home/work/school? Is it bigger than my chair? Do I see it commonly in the street? Is it alive? (reminding the students that plants are alive not just animals)
I have 3 rules to make it easier: It must be something you can touch, It can not be a person (teacher or famous person) and must be in the country we are in. This gives students practice in stressful situations and how to ask things in different ways to get the answer they want.
If they had not learned English basics from Kindergarten, start with greetings and work your way up with the most basic conversation topics. See what is trending in tween world (I really have no idea) for conversation teaching topics.
GOOD LUCK
