Explaining basic logic
The simplest and commonest use of the conditional is "If ...X..., then ...Y..." - meaning that if X applies, then Y is the consequence. For example, "If it rains, people get wet" - and the present tense is used here because the logic always applies, since in no known universe do people go out in the rain in order to get dry. It may help students to grasp this idea of 'always', not only because it is the kind of...