If you teach a lesson and your students don’t seem to be “getting it,” what do you do?

If students do not understand a lesson there could be several reasons.  However, one of the main reasons why students fail to grasp a concept relates to pre-knowledge and their existing knowledge structures which militate against any kind of understanding.  Learning is often sequential in some subjects and at other times it is dynamic but in most cases in sequential learning, the previous step must be mastered before introducting new knowledge.  In a dynamic learning situation once again its is important for information to be introduced in a way that learners can relate to it based on their existing knowledge.  In the case of the former and latter situations, the teacher must understand who he/she is interacting with and at what levels of functiong they are at.  In other words you may not be able to teach calculus to grade9 learners because much more knowledge is required before calculus is taught.  In most cases learners can be taught any subject, however, preknowledge and understanding the learner is critical for success.

As a teacher/ trainer, you must consider at all times that different individual learns different style. I strongly suggest to make the learning cycle an experiential one. Meaning, involve icebreakers, case studies and exciting activities. As a result, you'll be surprised that your learners are becoming more interested learners than before. 

To save the lecture at the very moment:

• Ask them if they have understood
• Ask them to tell you how did they understand it
• Explain it one more time in another way
• Try to use real life examples, case studies, parallels
• Include an activity / task that they will have to do

After the end of the lecture, review and revise the lecture... see if it makes sense

Revise lesson plans and add activities to engage the students.

rephrase it, give another explanation, put it in real worlds terms, show examples.... videos or art...

If students don't understand a lesson: -The teacher should review the methodology because a lesson is designed to be understood. It will be benefic to repete the lesson using others methods but also giving them concrete examples related to their environment (Case studies). -The course might not be interesting due to how the teacher is proceding. So the instructor must sometimes attract students attention by creating some small funny stories to allow students to relax their mind before continuing they course. I will like end up by saying, the teacher's mood or personnality can affect his course, thus He/she should be presentable, flexible and opened to the students.

I've no problem to repeat each single bit of the lesson, till all of them get it.

Identify the problem and change the technique. Before any lesson assess the students understanding method and make lesson plans based on that.

if the whole class is struggling with the lesson, it may be the syllabus has been badly designed and the lesson inappropriate at that point in time. Alternatively, it may be that the lesson is being taught badly. If this were the case, I would try to integrate the subject into something that motivates the class in order for them to relate better with the concept. The most important thing is not to panic as classroom management could quickly breakdown.

Make lesson more enjoyable for students,by giving different type of examples.most students want enjoyable atmosphere during the explanation, they want to listen something out of the textbook in the form of examples.if teacher not think out of the box, then student not attracted towards lesson.

If students are not getting the lesson it means either they are finding it difficult, boring, or teacher's language is not clear the method of teaching is difficult, the speed of teacher is fast,or may  be some disturbance from out side etc are the general reasons. the teacher should have to find the correct reason, try to engage the students , use the method of teaching which involve them in the learning process try to create healthy discussion so they can express themselves.