I offer groups for adults, teens, tweens, and families at my local libraries, and I'm happy to share what I've learned! (There's more than this one post in my brain, but these are the basics!)
My groups run like this - for the teens and adults we have about two hours, for the tweens and families an hour to an hour and a half.
Before the class: I always make up a list for every single ingredient I could possibly use for the group and check it twice to ensure I haven't forgotten anything. (The running joke with the kids is that I always forget something, but since I've started keeping lists on my iPod touch, I'm on a winning streak!) When you've finished the group, update the list to include anything you forgot for the next class.
Bring more than you think you'll need. People will go nuts making things once the idea clicks, and you don't want to run out. If you think you'll need 30 grams of citric acid per person, make it 60 grams because they will make more. Do set a limit - everyone is making 3 of something, but allow for mistakes!
It will take longer to make every project than you think! Last night's extravaganza was supposed to be five projects - candles, chocolate, soap, bubble bath, and Shrinky dinks - and we made it through three of them! So decide if you're prepared to go longer than you planned if you are running out of time or if you'll just leave that last project for another time.
Setting up the class: I like to have a head table where you'll find all the supplies, and a storage table to put our projects as they dry or set. I like to set the tables up in a square formation so I can approach them from either side. And let them get their own chairs - it saves your back and it allows them to sit where they want. Tablecloths from the dollar store are your friend - it saves you from having to clean tables for hours! And warn those people who might be scent sensitive or allergic to something if you are using ingredients that might bother them.
At the start of the class: Establish what you are making, when you are making them, and what they will get to take home with them. For instance, at last night's Christmas extravaganza (3 hours), I established we were making beeswax candles, then chocolate, then soap, then we'd package it all. Everyone could make at least two candles, a ton of chocolate, at least five little guest soaps, and they could use any packaging they wanted.
Offer a handout with recipes and instructions after you've finished your initial speech to the group. When you hand it out, they will start reading it immediately and won't be listening! I always put my e-mail, blog, and facebook group information on the handouts so they can get copies of it if they lose it!
And establish your expectations for the ingredients and clean up. For instance, can they bring the fragrance bottle to their table or should they bring their container to the fragrances? Should they leave the pipette in the fragrance bottle or on the table beside the bottle (I always leave them in)? What should they do with cups and spoons when they are finished with them? If you aren't using disposables, then establish an area where they should put your moulds and other items.
For our groups, I tell the youth they are responsible for putting their chairs on the rack, cleaning up the table top, and cleaning up the space under the table. If some of them leave early, then whoever is left at the table at 8:15 is responsible, which means that person will police the others. If they don't clean up, then there are random punishments in the future. It could mean no pizza at games night or they lose out on a project during another class. And they are random...they won't necessarily be punished at the next group but one in the future. I explain the reasoning for the cleaning in this way - it's our way of showing respect for the supplies, the facilitators of the group, your fellow youth, and the library.
At the start of each project: Show them how to make the product, then invite them to get supplies and start making it themselves or put the supplies on each table. I generally use this time to go around to the different tables and see how people are doing. If I see something particularly interesting or hear a good question, I'll yell out to the rest of the group this interesting thing! (And yes, with 23 kids, you do have to yell!)
I ensure there is a clean up in between each project - I don't want soapy tasting chocolates! Bring some crayons or grease pencils if people are sharing moulds so they can put their initials beside their project (and these clean off really easily). Let people know where the bathrooms are so they can wash their hands and let everyone know where they might find garbage cans!
If you're doing a group with tweens, remember they are accustomed to a classroom setting where getting out of their chairs is discouraged. With this group, I remind them they aren't in school and they may get up to throw away garbage, get more supplies, and use the bathroom (they don't have to ask me to go, but they should tell me they're leaving the room).
During the class: Encourage people to take their time with each project. This is one of the reasons I establish what we're going to make and what they're going to take home. If people think there's a limited supply of an ingredient, they'll rush through it so they can make more. I do a free for all at a certain point because I really don't want to take home a container of melted wax, chocolate, or soap - if we're making three soap each and everyone has made 3 soaps, then they can make another project but not before the others have finished their three.
In every group, there is one person who wants to make much more than you expect, regardless of age. If you say they can make two candles, they want to make four, and they'll be able to give you a really good reason for it. If you find you keep encountering these types of people, make it clear what you are offering to them, and hide your supplies because they will happily take more than their share.
Bring something they can carry their products home in, like some plastic bags. If you want to give them time to decorate cute packaging - which I like to do with chocolate or soap making - then make sure they will be able to take them home on bikes or if they're walking. I generally have cute cellophane bags and twist ties for the products and a Ziploc type bag for the transporting.
Bring labels! I get packs of Avery type labels and some felts so they can write down the name of the product (the kids love coming up with cute names for their products) and the fragrance. If they've done something different - for instance, adding flowers to bath bombs - they'll want to know that so they can replicate it at home.
Don't offer too many options. In my first classes, I would bring twenty fragrances and they spent most of the time smelling each and every one of them. I generally bring five now - for the kids, I make sure I have Pink Sugar, a fruity scent, vanilla, my current favourite (usually Cream Cheese Frosting or Clementine Cupcake), and something their parents might like, Black Amber Lavender or something more adult.
Remember that you're showing them how to make things, not to fill their homes with stuff. I used to worry that my participants weren't making a hundred things, but then I remembered that I'm there to ensure they are learning something they can make at home. For something like tea light candles, I try to offer five per person so they can try each scent and make a few layered ones.
Use disposable cups, spoons, bowls, etc. I know it's not the most environmentally friendly thing to do, but do you want to wash 50 cups and then find a place to store them?
There's a lot more stuffed into my brain, and I'll write another post on this topic in the future. Use the comments section to share what you've learned about offering groups or ask questions!