In Montessori elementary, we have work contracts (or work charts or work agreements or other names can be used). The concepts used for them, can be adapted to primary, and can readily be applied to the entire life of the family. Montessori didn't set out to establish an educational system; she observed, and found a way of life.
- You provide the keys (given in Montessori albums);
- you provide your own requirements (local educational requirements, family culture requirements);
- and you provide the child time to explore those ideas as well as his own ideas generated by them.
Did I just say "requirements" ???? YES! The children should have requirements (responsibility) balanced with personal choice/interest (freedom). Life is full of requirements, and we need to know how to work with our personal time too. So we start young and provide the children with (drum roll please) *REAL LIFE*.
SO. If you present the keys to mathematics, the child has LOTS of time to explore mathematical concepts, principles and history beyond the "requirements". Do they need more practice with their facts? then put in their weekly work contract that they will be working with the facts. As long as the child is showing responsibility, they have freedom of choice within the limitations you set (perhaps they have a choice about HOW to practice those facts). Not capable of the amount of freedom they have? Cut back to where they can have success; then give more freedom as responsibility is proven.
So.... can a workbook or textbook be used? Yes. But in *balance*. In the ordinary way of things within a Montessori classroom, textbooks are used as resources - not as the teaching manual or the set of requirements or even the main tool. But textbooks can be used as a tool; grammar books are specifically mentioned in the language album for elementary (mostly upper elementary) - we say "Let's see what this grammarian has to say on (a particular matter)". Workbooks are generally frowned upon, but that is fodder for another Nugget ;)
Caveat with textbooks: they are usually not primary sources. Get the children using primary sources as much as possible, but sometimes the children will be studying how different people interpret the same event or concept - therefore, textbooks make sense.
Or sometimes there is just no Montessori material available for something that a particular textbook or program covers very, very well (learning particular languages comes to mind - especially ancient ones). Combine the textbook with lots of real experiences and outings.
But remember: focus on the keys for what you the adult teach to the child.
Give them the tools they need to explore and have their own projects.
And if you have a requirement for their projects, then place it. It's ok! It's called living up to responsibility for fulfilling the local educational requirements (even when those local educational requirements come from mom and dad!). They should have lots and lots of time and opportunity for their work, such that the outside requirements can reasonably be met as a small part of their work cycle.
Then let them explore!