4Ls stands for Liked, Learned, Lacked, & Longed For. 4Ls is a popular, frequently used technique that is simple to set up for the facilitator and easy to understand for the participants. As with all retrospectives, 4Ls should be timeboxed. Depending on the size of the team, 30-60 minutes should be enough.
Step One: Before the retrospective starts the facilitator should hang four posters on the wall, one for each of the Ls.
Step Two: To start the retrospective the facilitator should explain the meaning of the four Ls. If the team is new to the technique, take some time to ensure everyone understands the importance of each L.
Step Three: Ideation. The facilitator should hand out sticky notes to the participants and tell them the timebox for this phase (10-15 minutes should be enough). Participants should keep their sticky notes private so that participants aren't biased by each other's ideas. When the timebox expires, the participants should place their sticky notes on the appropriate poster boards on the wall.
Step Four: Grouping. Since many sticky notes will likely contain related (or even identical) ideas, participants should group sticky notes into logical themes. Participants can use markers to draw circles around related sticky notes. The facilitator should announce the timebox (10-15 minutes) and encourage the participants to stand up and move from poster to poster to make this part of the retrospective interactive and fun.
Step Five: Dot Voting (optional). If there are a lot of sticky notes and/or groups to discuss, it can be challenging to structure the discussion in a meaningful way. If this is the case, the facilitator can opt to use dot voting to prioritize the discussion based on the collective desires of the group. The facilitator should announce the timebox (5-10 minutes) and, if the team has never used dot voting before, explain how it works:
Step Six: Discussion. The facilitator should announce the timebox for this phase (20-40 minutes should be enough). If dot voting was used, then the team should discuss the sticky notes in prioritized order. If dot voting was not used, the facilitator can choose the order of discussion. The facilitator can optionally choose to timebox the discussion of each individual sticky note as well (to 5 or 10 minutes). The advantage of this approach is that it tends to keep the conversation on topic and moving at a faster pace.