This includes asking questions, modifying or reformulating a question, providing clues and hints in order to help students provide a response, as well as encouraging students to ask questions and respond to each other.

Asking and modifying questions in class

Classroom questions tend to fall into two broad categories:

1. Display questions

These are designed to elicit learners’ prior knowledge and to check comprehension. They often focus on the form or meaning of language structures and items, and the teacher already knows the answer.

• What does ..... mean?
• When do we use .....?
• What comes after .....?
• What’s the opposite of .....?
• Where’s the stress in .....?

2. Referential questions

These require the learner to provide information, give an opinion, explain or clarify. They often focus on content rather than language, require ‘follow-up’ or ‘probe’ questions, and the answer is not necessarily known by the teacher.

• What do you think about .....?
• Have you ever....when/where .....?
• If you had .....what.....?
• What kind of .....?
• How do you .....?

The best referential questions are those that are ‘divergent’ or ‘open-ended’ in that they are broad, may have multiple answers, and require a higher level of thinking from the learners.

Open-ended questions are ideal for developing skills such as inferring, predicting, verifying and summarising, as well as eliciting more language. ‘Convergent’ or ‘closed’ questions have more narrowly defined correct answers which can be recalled from memory and require little reflection or originality. Closed questions are common in conventional tests.

Effective questioning

As with all aspects of teacher talking time, it is not the quantity but the quality and value of questions that is important. When thinking about their questioning technique, teachers might use the following as a check-list:

• Decide on the purpose of questions.
• Minimise the use of "yes / no" questions except when checking meaning and understanding or encouraging weaker students.
• Ask a balance of referential and display questions.
• Use open-ended (divergent) questions to encourage opinions, elaboration and discussion.
• Ask questions about important rather than trivial content.
• Grade language in questions and try not to over-paraphrase.
• Personalise questions where possible.
• Avoid questions that contain the answer.
• Make sure that students clearly understand questions.
• Spread questions randomly around the class.
• Balance questions to the whole class with individual student nomination.
• Give enough time for students to answer.
• Anticipate students' responses.
• Give appropriate responses to questions, particularly where correction is required. and in order to extend the dialogue.

Reference:
http://www.teachingenglish.org.uk/article/asking-questions

This includes responding to students’ comments and using praise appropriately. Here are the strategies:

1. Plain corrects

Providing a plain “Correct” or “Right” is sometimes more appealing to students as it can give a sense to them that you are treating them as intelligent, dignified people. Compared with some over-praise such as “Wonderful!”, plain corrects are simple judgement of the answer, instead of the students themselves. Plain corrects can also come with a restatement of information (Saphier & Gower, 1987), which can further reinforce the learning.

2. Incorrects with appreciation

Let’s take a look at this example:

“What you have said is a good trial. The best answer would be rarely for this question.”

This statement has changed the focus from the answer given by the student to their willingness to try and speak up, which deserves a praise. Students will then not be disappointed by the incorrect answer they have spoken and may even be encouraged to answer upcoming questions. This strategy is particularly useful for students with low self-esteem.

3. Silent response to errors

Throughout the interaction with students, you may notice some recurring mistakes such as confusion between “too” and “to”. Instead of repetitively pointing out the errors, you may note down these recurring mistakes and teach a lesson to cover these mistakes. By doing so, those who have already understood the concepts can have a quick review again and, those who do not can get a chance to learn it in a climate free of criticism or a sense of failure.

4. Honest and personal “I appreciate”

When a student answers a question correctly, if you are going to praise them, you may often say “Well done. You have given the exact answer.” This “you” statement is actually implying a judgment of one person over another. A better way to praise your students will be to start a statement with “I”, such as “I appreciate it” and “I like the way you said that”. This is less manipulative and judgmental.

5. Saying no slowly

Failure to hear out a student request can hurt more than an unwillingness to go along with it. The antidote is to listen carefully and be sure you understand before responding. You might also ask for more time to think it over or talk to others about it. And if you can't accept the request, speak warmly and respectfully, not coldly and curtly, perhaps saying why you can't grant the request.

References:
Harmin, M., & Toth, M. (2006). Inspiring active learning: a complete handbook for today's teachers (Expanded 2^nd ed.). Association for Supervision and Curriculum Development.
Saphier, Gower, & Gower, Robert R. (1987). The Skillful teacher: building your teaching skills (3^rd ed.). Research for Better Teaching.

The 6 Basic Types of Corrective Language Feedback

There are six generally agreed upon types of corrective language feedback, where the goal is to help students be accurate in their active use of the language by giving them information as to what is correct (positive feedback) and what is not correct (negative feedback) in the target language: clarification requests, elicitation, explicit correction, metalinguistic feedback, recasting and repetition.

• Clarification requests are where you indicate to the learner that there is a problem with the language output: The answer was not understood at all. There was either a mistake in the answer that could lead to different understandings (and therefore, clarification is needed) or there is a grammatical or usage mistake that should be corrected for accuracy.
• Elicitation is where after hearing the learner’s output, you repeat the sentence, pausing at the place where a mistake was made, thus giving the learner an opportunity to correct his or her own mistake by concentrating only on that word, phrase or grammatical construction.
• Explicit correction is where you simply provide the correct answer. This should generally be reserved until after several failed attempts by the learner to provide the correct output and when no other students are able to help. You should accompany it with an explanation of how to form the correct response, whether this is review or new information.
• Metalinguistic feedback involves explicitly stating that there is a mistake in the output and asking the student who made it or a classmate to find and correct the mistake.
• Recasting is where you repeat and reform the learner’s output, correcting the mistake along the way. Ideally the student or all the students will repeat the recast at that time in order to provide reinforcement of the correct language form.
• Repetition is where you repeat exactly what the learner has uttered, somehow emphasizing the mistake that the learner has made. This will indicate where the mistake is located, giving the learner a chance to focus on that particular part of the utterance and fix it.

In addition to instructor-led corrective feedback, peer-led corrective feedback is also possible. This is where students, working in pairs or in groups, help each other to learn by giving appropriate prompts, asking appropriate questions or providing appropriate explanations, when necessary.

The 4 Basic Types of Positive Language Feedback

There are four generally agreed upon types of positive language feedback: acceptance, acknowledgment, rephrasing and repetition. Here, the goal is to encourage the student to continue speaking, writing or otherwise using the target language or to indicate that the student’s utterance is correct or being understood.

• Acceptance demonstrates to the learner that you have heard, seen or read the reply, utterance or other form of language output and that it was appropriate to answer the question, prompt or assignment given. Acceptance is indicated by using words such as “yes,” “good,” “okay,” or similarly appropriate word or phrases in the target language. On a written assignment, you might put a check mark or a smiley face.
• Acknowledgement is any type of non-verbal communication, such as nodding or shaking of the head, making certain positive facial expressions such as smiling, giving a similar cultural-specific gesture or using verbal communication to indicate that you are listening and comprehending the language output. Examples of verbal communication could be “uh-huh,” “mmm” or any similarly appropriate word or phrase in the target language.
• Rephrasing is when you respond to learner output by restructuring the utterance to make it sound more natural, to introduce a new grammatical structure, to provide new lexical items or to add additional information that the learner either didn’t know or failed to provide. It is considered positive feedback because the original answer is still accepted as essentially correct.
• Repetition is simply when you repeat the learner’s correct language output so that everyone can hear the correct answer a second time, thus providing additional input for the language learner. Students may be asked to repeat the output themselves at this point for additional reinforcement.

Students, as well as instructors, can give positive feedback, and students should be especially sensitive to indicating that they are listening to their partner or within their group (i.e. using acceptance and acknowledgement as often as possible). Instructors can both model and explicitly discuss these types of feedback for their students.

Providing Meaningful Language Feedback in Oral Activities

Pinpointing is where you will localize a mistake, helping a student to identify it, without explicitly correcting it or giving examples of correct answers:

• Student: I’m going at the bookstore.
• Instructor: I’m going …
• Student: I’m going to the bookstore.

Cuing is where you will provide examples of correct answers to a struggling student:

Instructor: When is your interview?

• Student: My interview is at, um …
• Instructor: On Thursday? Friday?
• Student: Oh, my interview is on Monday.

Providing an example answer to a student who is struggling to begin language output is another option:

• Instructor: Where did you go on Saturday evening?
• Student: I, oh, um, I …
• Instructor: On Saturday I went to the grocery store. Where did you go?
• Student: I went to the bar.

Rephrasing a question with correct answer options helps when a student completely misunderstands the question:

• Instructor: Where are you going in June?
• Student: I’m going on the 6th.
• Instructor: Oh, okay, but where are you going? England? France?
• Student: I’m going to Denmark.

With proper modelling, your students will pick up on the feedback cues, and, when they engage in pair or group work, they will be able to help their fellow learners in similar fashion, thus diminishing the role of the instructor and increasing the role of your students in their own language learning.

Reference:
https://www.fluentu.com/blog/educator/language-feedback/