ou could make some changes in the classroom, something obvious, that they will notice as soon as they �ll come into the class. They will ask you about it but you can only answer with yes and no or you can tell them how you did it but not when...So after all questions are asked you can write on the board, "I �ve changed the ...." (NOT REFERRING TO THE EXACT TIME) and another sentence stating something like "I (past simple) the class last Friday".
Ask them to tell you what is the difference between the two sentennces and focus on the answers that indicate the fact that there is no time reference in the first one....then you know what to do...

 

You could talk about holiday or travelling destinations using a ppt with pictures of famous cities/sites around the world or within your country and ask the question "Have you ever visited / been to ...?". Ss could start by answering �yes, I have/ No, I haven �t � and then you could introduce the adverbs already and never. It always works with my students.