It is 9am. In St Michael's primary school near Lincoln, neat rows of parents are eagerly watching the teacher who is hamming it up at the front of the room. It is the last Saturday of half term. The teacher is Ian Harris, one of the authors of Mapwise: accelerated learning through visible thinking.
"Have you ever looked at your children after they have said something to you and wondered 'where did that come from?'," he asks. Nods of recognition.
"Then, when you're talking to them and you wonder 'is this going in?', sometimes it has when you think it hasn't and sometimes it hasn't when you think it has." Chuckles.
Then he comes to the point: "Have you noticed that we actually don't know what the other person is thinking when we are talking to them? Have you ever wondered whether you are having the same conversation? Each person is talking about the conversation in their heads.
"What happens," he continues, "when we make that invisible act of thinking visible?"
And this is what the workshop is about - parents in one room, junior school-aged children in the other, learning about how to map the ideas in their heads so that other people can understand them, and so that they can clarify their own thoughts.
The concept of "mind mapping" was invented by Tony Buzan and his brother Barry in the 1970s, initially for businesses. They copyrighted the term, too.
Ian Harris and his colleagues Oliver Caviglioli and Bill Tindall usually use the term "model mapping" for their version. They have done mapping workshops in many schools for hundreds of teachers, but that March Saturday in Lincoln was the first workshop for parents and children.
The idea was the brainchild of Liz Jones, head at St Michael's, one of six small schools comprising the Lincoln Learning Network. Parents and children from all the schools were involved, as part of the consortium's philosophy of partnership between home and school.
In the workshop, the parents discovered that maps can be used to show what children know. New learning can be added later. Maps can be created by several people so that they learn together. Most important, in the context of the parent and child workshops, they can help two people to have the same conversation.
Mr Harris says: "After today, your children will never be able to come home and say 'nothing' when you ask them what they did at school. You will be able to say 'show me'."
Even if they cannot articulate what they have understood, they will be able to map it out.
Thinking is non-linear. People do not build ideas in a neat sequence, as you have to do when writing an essay or a story. But once the picture in your head is mapped out on paper, it is easier to turn it into sentences and paragraphs. It is also easier for someone else - the teacher, a parent, a friend - to understand you.
The phrase: "I see what you mean" is entirely apt. Maps do not even have to use words. Pictures work fine. The process democratises cleverness.
Mapping is subversive. It gives children ownership of their learning. As Mr Harris puts it: "We are talking about understanding understanding."
Mapping helps people to make connections - not just between concepts and facts, but with other people. In their forthcoming book Think it! Map it! (Network Educational Press) he and Oliver Caviglioli write: "By revealing to learners how they process information, we can significantly and positively impact on their view of themselves. The learners now have the tools they need to collaborate and co-operate."
By the end of the school day the pictures in children's heads have changed.
New information has been added, new perceptions made, and perhaps some misconceptions have been corrected. A child's map of The Victorians, for instance, might gain a new byway for new ideas about the lives of chimney sweeps.
"There is no meaning in what the teacher says," Ian explains. "The child creates the meaning from what the teacher says."
Meanwhile, the children have been creating meaning from the words and activities of Bill Tindall, who has got them thinking about connections and categories. They are clear about the academic point of mapping - "It could help in the SATs when you are planning out a story," said a boy - but the emotional benefit is yet to be made apparent.
The revelation comes after lunch, when parents and children are brought together. Earlier, everyone had been asked to draw a map of themselves.
Now, each child-parent pair is told to explain their maps to each other, and then to explain the other's map back to them. It is hard to hear what the pairs are saying to each other as you walk around the room, but their expressions tell the story.
The smiles of recognition, the laughs, the meaningful looks, the intimacy are moving to see. You can guess where parent and child have recognised that they felt the same way about a shared perception or experience.
Cliches like "quality time" do not express it. Perhaps "equality time" is better. One girl described it as "an opportunity to share how we think and understand each other".
Model Learning, directed by Ian Harris, runs mapping workshops.