The answer to the majority of problems the world is facing is community - we need to rebuild real physical communities, participate in them, and nourish them. We can do this by simply getting more involved in existing ones, staring from things as simple as local gardening groups, litter picking/beach tidy groups, community celebrations, local markets, etc. We need to hold on to, strengthen and rebuild arts groups and help local arts and music scenes to grow.
We can all participate on some level in some aspect of physical community building, and it will enrich us in a way social media never can. (Put on a gig, attend an arts show, donate to a community group, talk to neighbours, support the vulnerable). I believe people feel so isolated and depressed by the way greed has ruined the web, jobs, the economy, etc.that the time is right for many more people to start investing time and effort in real communities.
We need to build and grow communities in a local, regional, national and international spirit. We need to learn how to share, and how to get rid of greed and selfishness in ourselves and in our societies - participating in and building welcoming, non discriminating communities is the path towards this. We need to remove competition in education, arts and science (and ultimately economy), and focus on cooperation and improving things out of the joy of helping yourself and others. Communities can bring this about, and digital communities (as opposed to competitive social media) can support this, too.
Ideally, we want to grow communities in a way where people start thinking first “how does this help my community?” - especially when looking at political and business decisions. We need to feel something positive to stand up for (not old fashioned ideas of ‘country’ or political groups) - we simply need mutually supportive groups (communities) that fight power, greed and selfishness to defend people, animals and nature.
Audio engineer here. Definitely don’t get a directional mic like a shotgun (fuzzy) mic or a cardioid mic (like singers use on stage). These require at least an audio interface, careful placement and multiple mics. For your situation, something like a Zoom H2n will be the best and perhaps cheapest option. It has 5 built in mics, so you’ll be able to capture sounds from all over the lecture hall. Use the 4 channel surround option, or the X/Y or Mid-Side options, and see what works best. It won’t be perfect, but it will be the easiest option to improve audio and simplify recording. Plus, the batteries last for many hours (ideally use the best rechargeable Eneloop Pro AA batteries).
The professional way to do it would require a mixing desk, an expensive DPA, Shure or Sennheisser lavalier mic on the lecturer, at least 2 room mics and possibly a boom operator with a shotgun mic to capture audience questions. (Although this last option could be replaced with room mics or additional fixed mics pointing at the audience). There are various options for room mics depending on the acoustics of the room, and there are no one size fits all solutions for professional quality audio.
But you don’t need professional quality, just the best you can get. With a Zoom H2n, you can put it on a tripod near the lecturer, and it will pick up sound better than average human ears. It will be better on a tripod, because it won’t pick up floor noise as much. To reduce floor noise further, get a decoupler to reduce handling noise and use a mini tripod sitting on a desk or chair. If the lecturer hall is windy (lots of air conditioning or windows and doors open) use a windshield.
You could use any handheld recorder that does X/Y recording and it might be fine. But 4 channel recording might help pick up more from the audience, and you can still boost the lecturer’s audio by keeping the device close to them and having the “mid” mic pointing at them. The recordings can be fiddly to edit at first (especially if you want to boost part of them, like the “mid” or “sides”, but it doesn’t take long to get the hang of it. Use Audacity to edit the audio or any free audio editor you happen to have access to.
Please feel free to get in touch if you have any questions, and good luck with it!