I myself thought up two sentences:
- The children played in the sandbox.
- The children have played in the sandbox.
The only difference that I am able to recognize is that in the 2nd sentence we are putting some emphasis on the fact that children (have) finished the play. If I translate "have" into my language then it is giving the emphasis that children finished the job. On the other hand the 1st sentence is just telling that children played there some time ago. The 1st sentence is giving no emphasis on the fact that they have finished the play.
Please explain me what is the difference between Present-perfect-tense and Simple-past-tense.