I have Cubs rather than Brownies - but mixed group.
We do some craft things - like recently made a card per Patrol for a fellow Cub who was in hospital. One leader brings in his equipment every few years and they make wooden woggles, and another (tries to) teach the Turks Head woggle.
We do a couple of sessions on knots a year - learning them, games with them, and doing some pioneering (one leader made a model raft and model rope bridge small kits, using thin rope, broom handles cut into lengths and empty water bottles as the floats).
We take them on 2 overnight hostelling trips (involving a long hike and evening campfire on each), and a 2 night camping trip just before the summer break.
We try to do a litter pick with the rest of the Troupe. Sometimes there is too short notice though.
We have "Danger Day" early on most years - learning the Den and dangerous parts (and why - like never drink the water from the Burco Boiler as it's hot and will burn your lips, ask how one Cub learned that!), doing our fire drill, learning the important safety signals etc. And playing a game that is risky but controlled...chair relay.
We work on scouting skills (Brownies should be doing some of these too I think) like planning ahead, what gear to wear outdoors, how to pack rucksacks, how to pitch and strike tents, how to find shelter, how to read maps and navigate, safe use of knives (pen knifes are popular to whittle marshmallow sticks for campfires). When we are on hikes, we will show the maps and routes, and how to find features out in the outdoors. We've done backwoods cooking in the yard of the den (on the fire grates that scouts use on camp) - just using sticks and tin foil (or orange skins and scooped out potatoes) to cook in/with.
We talk about the environment and different types of trees/plants/animals etc, what we find on camp, how its different to what's around our Den, and our "Outdoor Den" (a large park nearby that we have sessions in relatively frequently as we meet on Saturday mornings).
The other Cub unit does a session each year to sew on their badges, with 1 leader having an ironing board and steam iron in the galley (kitchen) of the Den where each Cub goes and irons their necker.
There are lots of jokes and stories, and games, and some singing.
There are lots of activity sheets, colouring sheets, word searches etc that you can use to make a topic more interesting. And there is usually some game you can play to reinforce the learning, and have some fun.
We also do a lot of boating as we are a Sea Scout Group, so that takes about 10-12 weeks of our roughly 32 week annual programme. (And we try to do one session on boat maintenance, and we also have another session on theory of boating and parts of boats, and a discussion about water safety as part of a session before boating season, annually).