Write their answers on the board then get them to infer the use/meaning of the past perfect   (I personally like to call this tense " the past of the past" ) and its form. After this presentation phase let you pupils have some controlled practice ( a word building task for example) and some free practice (writing a short narrative text using the past perfect). 

I hope the tips above will help.

I often tell my students an anecdote where I use both tenses and put the verbs down on a timeline as I go along using two different colours for the two different tenses. Then I write down a couple of complete sentences above these verbs and draw arrows on my timeline to show how the past tense is linear whereas the Past perfect is like a flashback going further back in time. I don �t explicitly state any rules at this point. I ask quest ions like " did I do this before or after that". Then Students make their own time line of verbs next and talk to each other. Monitor. Choose 1 interesting story and put the timeline up on the board- Ask questions and draw arrows on the time line to indicate the tense as you write the sentences the students make on the board. Long winded :-) but works well.

Cheers!