Thinking in pictures will help kids understand the concept well. I drew three trees. The tree that was grown in the past is the tallest, the present tree is growing but not as tall as past. The future tree is a dotted tree and addressed as virtual. Each tree has four branches, a simple branch with no leaves or one leaf, a continuous branch from which leaves are falling continuously, a perfect branch that has three perfect leaves and a perfect continuous branch that has three leaves falling continuously and three leaves perfectly replaced. These pictures with examples is an impactful way of understanding tenses. Do try it.