Training a room that already knows this

Because there is no middle. A room split between ten-year veterans and week-one hires is two rooms wearing one meeting invite, and the average of their needs describes nobody in it.

Teach to the average and the veterans check out in the first fifteen minutes while the new people are still lost. You lose both halves and the feedback form tells you the session was "fine".

Give them a job. Not a courtesy role, a real one: they hold the hard cases. When you introduce a concept, the veterans supply the exception from their own work and the newer people hear what the edge of the rule looks like.

This works because expertise wants to be used, not flattered. The fastest way to lose a ten-year practitioner is to explain their job to them. The fastest way to keep them is to ask what breaks.

Name the floor out loud at the start. "By the end of this hour everyone in here can do X" sets a bar the beginners can reach and tells the veterans what is not the point of today.

Then protect the first exercise. The first time people practice is the moment beginners decide whether to participate for the rest of the session, so pair rather than volunteer, and never open with a cold call.

Sometimes, and if you do, split by what they are practicing rather than by how long they have been doing the job. Splitting by tenure labels people in front of their colleagues and produces one room that feels remedial.

Splitting by task reads as sensible. "Take this scenario if you are handling it for the first time, take this one if you have already handled three" gives people a choice they can make privately.

Ask both halves for something different. From the beginners: name the one thing you will do differently on Monday. From the veterans: name the one thing here you disagree with and why.

If your veterans have nothing to push back on, the material was too safe for them and they were being polite. That is worth knowing before you run it again.

Want to practice this in front of someone?

Mixed rooms are one of the scenarios in Where Sessions Break, which runs two live sessions capped at twelve people.