A list I've accumulated from multiple places, so can't vouch for all of them, and definitely there's no empirical evidence I know of for these improving epistemics, but I wanted to collect the list anyway.

The obvious place to do these is in student groups, but I think limiting them there is a mistake. I think we all can benefit from honing our skills, plus a bunch of these are just fun. If you play board games or do Puzzled Pint with your friends or coworkers, then these can just be part of that part of your life.

Will be editing and adding to this over time - what would you recommend?

Activities

• Thinking Physics questions
• Fermi estimates / Estimathons
  • Sample estimathon questions
  • Rules for estimathons from Berkeley, which probably came from Jane Street
  • List of lists of Fermi problems
• Calibration training
  • Sage Calibration Activity (my current favorite) 
  • Scout Mindset Calibration Questions
  • Open Philanthropy's Calibration Questions
  • More in this wiki
  • I have more if you DM, don't want everyone to know all the good questions ahead of time :)
• Team Forecasting - really excited about this, watch this space, but in the meantime, nothing stopping you from just picking a question from Metaculus or Manifold and discussing together
  • I had a great time recently pastcasting a question with a friend, which had the added benefits of getting both of us smoe knowledge about the current conflict in Ethiopia
• Resolve the Abilene paradox (A type of groupthink)

Games

• Wits and Wagers (Someone else's experience of using it in EA contexts)
• Murder, She Bet
• Betting Market Game Night
• Poker
• Fermi Poker
• CONFIDENT?
  • It's basically a competitive gamification of calibration training. You are rewarded for having the smallest confidence window of all the players, and penalised if your answer is outside of your confidence window.

Talking

• Explain or draw how something works, notice where you falter, let someone pick up the slack from there

Writing

• Fact posts
• Minimal trust investigations
• Learning by Writing
  • Related: Putting Ideas Into Words
• Learning by writing in groups