I'm not great with mess. I do everything I can to avoid it. But if you have a toddler it is inevitable. The key for me is to know what is true mess and what is the child's work or play and to contain the mess as much as I can.

It is important to me not to view mess as a negative and not to use negative words or negative body language around it. It is also really important to make cleaning up a part of the activity and always prepare for it. Here are a few ways we are containing and managing Montessori mess in our home:

• For outdoor play have a transition area - this can be the mud room, front porch or entry-way. A tray for muddy rain boots (wellies) is a good idea as well as a small chair for the child to sit on and a basket or hook for coats. We also have a plastic bucket in this space in which we can place any soaking wet or really muddy clothes or coats that need to go straight into the wash. It depends on the weather and how much wet/muddy play your children enjoy but a small hand towel might be a good idea in this area too. 
• For baking use an apron - this is so hard for us right now, Otto often doesn't want to wear an apron but it's worth persevering. 
• For art consider using an art apron or waterproof smock - for activities like painting, we currently use a full arm-length smock that goes right down to the wrists and has a close neckline. It is easy-clean and (so far) stain resistant. It depends on the activities you do, currently our art smock needs to be waterproof but for older children, a cotton art apron might work ok. 
• For really messy outside play for toddlers and preschoolers look for an all-in-one coveralls or splash suits (in the UK I like these). It will protect their clothing and still allow them to be involved and participate in muddy, wet or dirty play. 
• Look for natural but washable art materials and supplies. It's not fun after allowing the child to use finger paint to find it has stained their hands, arms, face and clothing. There are a lot of washable art materials for toddlers from paint, fingerpaint to markers and even washable stamps and stamp pads. 
• Allow enough time for clean up - for us, this often means allowing 20-30 minutes after painting or outside play for a bath. In the bathroom I always have a small stack of clean face washcloths within the children's easy reach (even for the toddler), this allows them to spot clean or wash their faces themselves. As much as possible allow the child to work at their own pace so allow extra time, it might take me five minutes to clean the table and sweep but it might take a toddler 20 minutes.
• For water play always have more towels nearby than you expect to use. Keep them within reach too, I don't want a toddler slipping over while I run off to get the towels. 
• For really messy arts and especially for toddlers work outside or in the kitchen (on tiled or easy to clean flooring). Outside is often a good option to get the benefit of outdoor play but isn't always possible.
• For lots of practical life work the key is to do it more often. This is the same with self-feeding and activities like pouring a drink from a pitcher or water dispenser, baking or chopping foods. The more often the child does it the more likely they are to master the skills sooner and make less mess. I hope most families will make activities like this an everyday occurrence or maybe even multiple times a day. 
• For children's tables look for non-absorbable easy-clean table surfaces or consider a wipeable tablecloth (perhaps laminated) for art areas, it will prevent staining on wooden table surfaces and make clean up easier. Otherwise sealing the wooden table surfaces might help. 
• As much as possible involve the child in clean up - this may help to contain or reduce the mess in the future as the child may be able to make an effort to make less mess next time and be aware of exactly how much mess they make. It helps to have some child-size tools available like a small broom, dustpan, mop, perhaps a hand-held duster buster type device. 
• Supervise. With three children this is really important. I know what mess is acceptable and I always keep an eye on the kids to make sure things don't get out of hand. I (of course) allow them to have fun but wouldn't leave three of them alone with a lot of paint or paint/permanent markers for example. 
• Allow the child to do their work in a tray. For Otto especially this helps him to contain his work. When he plays with playdough he likes to tear it into little pieces, so it's easier for him to work in a tray. Often when he is cutting, using a slicer, I will help set the work up in a tray. I like the white melamine trays with a low edge, the edge is important but not too high so that he can still easily reach inside. 
• Keep cleaning materials in the child's workspace - for example a small sponge and spray in the child's kitchen area or a bin near the child's art shelves. Observing the child working and cleaning up will allow you to know what materials are required. 

We don't want mess or the fear of mess stop us from working and playing with our children. We also shouldn't (I am so bad at this while baking) interrupt or break the child's concentration to clean or start tidying up while the child is still working. While some families are just messier or can tolerate mess better, it is important that children know how to clean up (the skills and steps required) and that we need to clean up in order to take care of and respect our home, our materials and each other.