A tense is a grammatical category that locates a situation in time, to indicate when the situation takes place. Some typical tenses are present, past, and future. Tense can make finer distinctions than simple past-present-future; past tenses for example can cover general past, immediate past, or distant past, with the only difference between them being the distance on the timeline between the temporal reference points. Such distinctions are not precise: an event may be described in the remote past because it feels remote to the speaker, not because a set number of days have passed since it happened; it may also be remote because it is being contrasted with another, more recent, past event. This is similar to other forms of deixis such as this and that.
Learners spend a lot of time studying different tenses so Busy Teacher has collected 3,571 excellent worksheets on tenses and even sorted them into subcategories to make your search for the perfect worksheet even easier. Many teachers have devoted preparation time to this topic so that you do not have to. It is hard to choose a worksheet to examine but here is one that seems to be quite popular. The board game is designed to be a review of tenses and can therefore be used in any class. Students play the game in groups and must make a new sentence every turn. Other worksheets focus on specific tenses so one of them may be more appropriate if you are not currently in a review stage.
Where to begin? There are a lot of tenses that students need to learn during the course of their English studies. Their native language may determine how difficult students find this particular topic. Some languages are more similar to English than others and students who speak those languages will therefore have an easier time in your class. Tenses are almost always taught in the same order. Beginners start with present simple before learning the simple past and then simple future. As students progress they are introduced to more and more tenses until they have mastered them all.