I had heard about 'control of error' before on other blogs, but I had never really heard a good definition of what it was until I read John Bowman's e-book Montessori at Home. Here is an excerpt that I found particularly helpful:
"Mistakes are how we learn. Imperfection is expected. Even after we achieve ‘mastery’ of a
task, mistakes still happen, though not as often. If your child does not make a few mistakes and
have a few accidents, she isn’t learning or isn’t interested. Mistakes when learning are OK.
Dr. Montessori had a different term for mistakes – Control of Error. She designed her materials
so that a deviation from what was supposed to happen immediately tells a child that there has
been an error. Children will not necessarily see one outcome as desirable over another. When
you demonstrate activities for your child, always demonstrate what to do if there is an error.
Always use a plastic or other table mat when doing these activities. Have a sponge and
cleaning cloth ready. A mistake, such as spilling a bean during a pouring transfer, is actually an
opportunity. When it happens, don’t make a big negative out of it, just be sure your child stops
the activity and picks up or cleans the spilled item up before continuing. That spill was the
control of error for the activity – a signal that something went out of normal. Mistakes are
actually a teaching moment. They should not bring a negative reaction. They are just things
that happen and need to be fixed before continuing on. All these experiences are teaching your
Let’s say you are showing your child how to pour rice from one cup into another. Make sure
you drop a little rice onto the table or floor. Immediately stop pouring. This tells your child
that something unexpected has happened that needs attention. Carefully pick up all the rice
that spilled and put it back into the cup. Then resume the pouring. Your child now knows that
spilled rice is an unexpected deviation from the desired outcome; and that it needs to be fixed
Without this step, your child may not see any difference between rice on the floor and rice in
the cup. Always include an example of how to handle errors when you demonstrate an activity
for your child. Spill some water and show your child how to use the sponge and cloth to clean
it up before continuing. Let your child practice this."