[susan53]

You don't say why your tutor didn't like the lesson, and I can't find the activity which you used, but I would guess that the problem was that it was a practice activity which you were using when you needed to be presenting the language. You can't expect the students to use the language until they've heard it, they've understood the grammar and they've had a chance to repeat it and use it under controlled conditions.

You have the disadvantage that you only have 12 mins - nothing in classroom terms, and the advantage that they already know the present passive and its use and, presumably was/were. Given this, they should be able to "invent" the past passive for themselves without too much difficulty

I would introduce the past like this :

a) Show the Ss 6 pictures or objects in pairs of 3 – one singular, one plural. I suggest : places -The Taj Mahal and the pyramids; some well-known books – eg Lord of the Rings and 2 or 3 James Bond novels; objects – a wooden ruler and some ballpoint pens . The students must know the places/books for this to work. Check that they recognise them /know their names (What’s this? / It’s …; What are these? /They’re …) and list them on the board in this order :
The ruler …
The pens …
The Taj Mahal …
The Pyramids …
Lord of the Rings …
The James Bond novels …

These are the beginnings of the sentences which they will write in stage 3.

b) Tell the Ss you’re going to describe the things, and they have to listen and identify them. Say each of the following sentences two or three times as necessary. (NB I am assuming that the students will already know the verbs used. If not, then you’ll have to change to different objects which can be described using verbs which they do know) :

These are made of plastic
This was built by an Indian prince.
This was written by Tolkien
These were built by the ancient Egyptians
This is made of wood.
These were written by Ian Fleming.

The students simply have to understand and call out the names of the objects.

c) Pair the students and ask them to see if they can remember what you said about each object. Give them the option of hearing all the sentences once again before they start, and then do the first, The ruler is made of wood at class level. Complete the sentence on the board and check that they remember the formation of the passive and its use.
Tell them not to do the sentences in order necessarily, but to work first on those they remember best.

d) When they’ve had a chance to think about them, stop the pairwork and ask them for the sentence about the pens. Use the ruler/pens to point out the singular/plural difference, and then use what they come up with for LOTR the pyramids to point out the use of the past of BE (sing/plural) for these past events. If they've used is ask : Is it present or past? What's the past of BE? Give them a chance to check what they wrote for the last two before you elicit the answers and write them up.

e) Repetition work (backchaining) on all the model sentences.

Ideally I’d want 20 mins for this (5 mins per stage). But I can’t see how you can do it more quickly. 10 minutes is unrealistic for a structural presentation. You might be able to condense the first stage by putting the pictures and the names on the board before the lesson starts.

Hope that gives you a few ideas.