This post is for Tiffany who had some terrific questions for me. First of all, thanks for visiting the blog! Thank you Serena for sending your friend this way :)
So, to answer your questions:
We meet once a week during the cold months. Last summer we tried to meet twice a week but the second meet-up was much more unstructured (no formal lesson plan, more child-led exploring, etc). In the summer, when kids are out of school and the weather is nice, people seem to have much more flexibility and time to play outside.
We have about 5 standard, kid hike-able spots that we go back to often but I throw in new places all the time. We usually go a little further afield once every two months (to an old growth forest, a farm, wetland, etc.). I try to connect our location with our theme. If we are learning about frogs, we go to a wetland. If we are learning about trees, we go to the woods. If we are learning about flowers, we go to a place where lots of wildflowers are growing, etc. I like to pick places without a playground. I find that if there is a playground, the kids are so drawn to it and its difficult to get them to want to explore the unmanicured and natural areas.
I don't have a good answer on my approach for each week. This week, we learned about trees because my 4 year old had been asking if we could go into the woods and find a good climbing tree :) I definitely make an effort to tie the seasons in with our lessons. For the month of November, each week we focused on things we are grateful for (the earth, our families, our senses, food). Sometimes I ask the kids what they want to learn about and I use that I a place to start. Last year, I remember asking the kids and they all wanted to learn about dump trucks or tranformers or something like that! I don't think I ever ended up doing a lesson on dump trucks but the kids sure love talking about what they are interested in :) Once I figure out what I want to teach for a specific week, I scan the internet for ideas, go through files from when I worked as a field trip teacher at the arboretum, or I think up things while I'm trying to fall asleep! If you need ideas, feel free to ask. I have so many lesson plans and I'm planning to post them all eventually.