Do you need to show how the tense backshift works in Reported Speech in one place? Here's a grammar guide which summarises the changes in tenses in Indirect Speech. It highlights the importance of the reporting verb's tense, which points whether there is a change or not in the reported speech. The grammar guide tries to group the same tenses in one column, which will help your students remember them while producing an Indirect Speech.
You can either use it as a grammar reference handout and go through the first handout with your students and emphasise that we don't make any changes in the tense when the reporting verb is in present or just place the second handout on classroom walls as a reference point in class.