Set up a 'retrospective mailbox' at the beginning of the iteration. Whenever something significant happens or someone has an idea for improvement, they write it down and 'post' it. (Alternatively the 'mailbox' can be a visible place. This can spark discussion during the iteration.) Go through the notes and discuss them. A mailbox is great for long iterations and forgetful teams.
Group discussion with varying subsets of participants Source:
Place at least 4 and at most 6 chairs in a row so that they face the group. Explain the rules:
Take a bench seat when you want to contribute to the discussion
One seat must always be empty
When the last seat is taken, someone else must leave and return to the audience
Get everything going by sitting on the 'bench' and wondering aloud about something you learned in the previous phase until someone joins. End the activity when discussion dies down. This is a variant of 'Fish Bowl'. It's suited for groups of 10-25 people.
Divide a flip chart into boxes headed with 'Start', 'Continue' and 'Stop'. Ask your participants to write concrete proposals for each category - 1 idea per index card. Let them write in silence for a few minutes. Let everyone read out their notes and post them to the appropriate category. Lead a short discussion on what the top 20% beneficial ideas are. Vote on it by distributing dots or X's with a marker, e.g. 1, 2, and 3 dots for each person to distribute. The top 2 or 3 become your action items.
Gauge participants' satisfaction with the retro on a scale from 1 to 5 in minimum time Source:
ALE 2011, Corinna Baldauf
Put sticky notes on the door with the numbers 1 through 5 on them. 1 is the topmost and best, 5 the lowest and worst.When ending the retrospective, ask your participants to put a sticky to the number they feel reflects the session. The sticky can be empty or have a comment or suggestion on it.