A Dalton assignment is a contract

Yesterday I could work with the team of teachers from this school
in Rotterdam.
The topic of the workshop was:
'How to make an assignment'.
The group of teachers discussed and worked with topics like
* differentiation in design
* registration and self correction
* free-choice-assignments

But the most important issue was the discussion about the difference between a task / assignment and a contract.
Helen Parkhurst emphasizes the influence of the pupil on its own work.
The pupils must be stimulated to take initiatives and to take more responsibility for their own learning process.
Using the word contract instead of assignment has as result that the teacher is more focussed on the necessity that pupils must have influence on their own work.
Distributing attractive worksheets is in some cases a pleasant break of the normal process, but its not based on the Dalton assumptions.