In the last video you learned a little of the theory about the likely difficulty of a question for ESL students. Now let's consider the practical implications of this theoretical knowledge. There are two things to bear in mind. Firstly, in general, you should start a lesson or session with some quick closed questions before moving on to the open questions. For example, you could ask the closed question: "What do we call the number below the line in a fraction?" This will give even the students with very limited English the chance to answer, and will boost their confidence. The second thing to bear in mind is that when you pick a student to answer, you should match the question to the student's language ability. Don't ask open questions to students with very little English. Conversely, don't bore good students with a series of simple closed questions; challenge them with open questions that will provoke thought and require them to produce longer, more complex responses.
There are three more important aspects of asking questions that need to be considered. The first is wait time. Wait time is the time that the teacher waits after asking the question before choosing someone to answer. Of course, sometimes teachers do not wait and allow students to shout out the answer without raising their hand. This kind of questioning is actually not helpful to ESL students. It does not allow the slower students in the class to even finish processing the question before someone else has given the answer. They will soon shut down, if they feel they never have the chance to participate in discussions. So, in most cases, you should require students to raise their hand if they know the answer to a question. And then wait a few seconds before choosing someone to answer.
A related issue is whether you should disallow hand-raising altogether, and pick the student who is to answer the question. The advantage of this is that all students can be called on in a lesson, and so be made to feel they have a part to play and are not overshadowed by the quicker or better students. In general, though, this advantage is outweighed by the disadvantage of the embarrassment caused if the teacher asks a question that the student doesn't understand or cannot answer. In general, it is better to only pick those students who raise their hand or indicate in some other way that they know the answer. But then try to make an opportunity during individual working time to go to the slower or less proficient students and ask them some easy or closed questions to develop their confidence.
Finally, it should not only be you who asks questions. Students should be positively encouraged to ask if there is something they don't understand or that they want to know. They will be much more comfortable doing this if you can create the trusting, friendly relationships mentioned earlier.