Pupils interact all together and agree to create the model of their classroom in legos. Then, they compare their model to a photo of their class. Together they try to straighten and correct if necessary, add the names of their friends and put them at the right place. Then, they draw a plan based on their model. The role of the teacher is just to guide pupils if they need to, but he is supposed to be just an observer and hears what pupils say and answers the questions: What is a plan ? Why creating a model?