Time needed: constantly 1 – 2 min
Why? Students who have questions are interested in the subject and topic.
When? Any time.
How? If you think about the how, you maid think ‘ya questions will come all the time, students will ask by-self’. Yes if they are interested in the topic probably, but what about the situation that students are not interested? The answer is simple: as more interesting you create your lesson, as more you can expect that students will ask questions. Never finish a topic without forcing questions. Give in the end of any lesson an interesting point for the next lesson, so that students will have the chance to search and to be able to ask questions in your next lesson, make them interested in your topic, as more as you are interested in your own topic, as more you are searching for new information, for new daily life connected facts, as more students will be able to follow your curious energy.
Any risks? As long as students ask questions, as long they are following actively your class. Questions are good features of an interesting class. In general you can measure the quality of a lesson by the amount of questions which have been asked.