Having completed a unit of study on magnetism, it only makes sense to introduce the children to some of the natural laws associated with electricity. The main sensorial key for introducing electricity in the Montessori classroom is allowing children to construct a simple electrical circuit with a small lightbulb as a load.
The children delight in constructing the circuit, learning basic nomenclature (electrons, source, load, and return) and learning that electric current only flows in a closed path (the electrons have to get back to where they started).
I happened to have several prospective families come to tour the school while children were working with this material, and I cannot even begin to explain their amazement at the children's ability to assemble the circuit and explain to outsiders what they were doing. In every case, the visitors commented to me upon what a clever lesson it was and how they would not have considered teaching something like that to children this age. As always, I find myself able to tell them with pleasure that this lesson was not my invention. Montessori was always ahead of her time. This science lesson is standard fare for children in this plane of development (in fact I have a copy of a write up of this lesson from the Maria Montessori Training Organization in London, which was opened by Montessori herself, from 1947). In fact, it was members of the American scientific community who first welcomed Dr. Montessori to America and embraced her beliefs; Thomas Edison and Alexander Graham Bell invited Montessori to America for her first appearance in 1915, and the first Montessori school in America was established in the home of Alexander Graham Bell.
But I digress... In any event, suffice it to say, I am reasonably confident that children today enjoy their first foray into the study of electricity as much as the children one hundred years ago.
When presenting this unit, it can be fun to try a little experiment with yourself: If you have correctly sequenced the units of study and the scientific materials in the classroom (in which case you will now have a magnetic sorting lesson on the science shelves in close proximity to the electrical circuit work), if you have provided the right classroom atmosphere (which encourages intelligent experimentation), and if you have given the right hints and cues to encourage the students to reach a higher level of thinking (scaffolding), your classroom will spontaneously (without your giving any type of presentation at all) arrive at an understanding of insulators and conductors. It is a really fun phenomenon to behold!
Generally, one very observant child will begin to see that just touching the copper wires to the terminals causes the circuit to work and from there they will begin to wonder what else they could touch to the terminals to have the same effect. Soon, they will notice that some materials can conduct the current, while others do not. They will inevitably go and get the magnetic sorting lesson (sorting objects into magnetic and non-magnetic) and try using the different items in the box, and will not fail to notice that the items that were magnetic are also the items that conduct electricity. At this point, the guide should supply the appropriate vocabulary to their discovery. The excited child will inevitably go around the classroom sharing his or her discovery with the other children (it they have not already crowded around to watch the experiment unfold).
This type of autonomous learning, the "ah ha," the exhilaration of having discovered something for themselves, is absent in classroom environments where teachers present concepts and information to children, rather than creating the conditions in which they can discover it for themselves. That is the beauty of Montessori. Everything is available to the child and made ready for her, but nothing unnecessary is done for her. Unnecessary help is a hindrance to development. The task of a Montessori guide is to invite and challenge, direct and learn, nourish and care, but also to stand back and observe these inquisitive and industrious minds at work.
Once the children understand the basics of an electrical circuit and insulators and conductors have been discovered, it is time to introduce them to a generator and the ways in which magnets can be used to make electricity. Our little generator uses a small hand crank to turn a single alnico magnet which lights an incandescent lightbulb (you could also use a compass as the load).
"I did it! I made electricity," one little three year old could be heard exclaiming the first day this was out in the classroom. I had to laugh; I am pretty sure that in this age of ipods, DVDs, Leapfrogs, and television, there aren't children anywhere that are more excited about being able to illuminate a lightbulb!