Human brains are flexible, but the systems they devise are not.
So it takes planning, motivation and commitment to replace a curricular structure that suits the educators with one that meets the needs of those being educated.
Curricular flexibility is about motivating young people, linking their school experience to their future lives, and achieving the decades-old dream of the comprehensive school, says Michael O'Neill, North Lanarkshire's director of education.
"A school cannot be called comprehensive if it does not allow all pupils the opportunity to develop their skills, but affords that opportunity only to a small group. That's a key point about curriculum flexibility."
Recent experience in two North Lanarkshire schools illustrates the features, challenges and benefits of a more flexible curriculum. At Dalziel High, in Motherwell, the entire third year is about to sit Standard grade English and maths exams. Pupils are confident but teachers are a little bit anxious.
"We'll be keeping our fingers crossed next week," says Brian Miller, the headteacher. "We have never presented a third year for Standard grade before, so there is a great deal of interest, inside and outside the school, in how well they perform."
The pupils are every bit as well prepared, he believes, as their fourth year colleagues, who will sit the same exams at the same time, and there are good reasons to believe that their efforts will be crowned with success.
Six months ago the third year pupils had no experience of the pressure of performing in an exam hall under SQA exam conditions. Now they do. Prelims have been sat, the results analysed and appropriate action taken to address the issues raised.
Lack of maturity had been flagged up by the English department as a possible problem. "Not so much in terms of behaviour," explains Anne McCartney, the principal teacher of English. "What concerned us - teachers and parents, although not the kids - was that they might not be mature enough to do a good job of Standard grade English, particularly the writing element."
After monitoring the pupils' progress closely throughout their second year, the school found that their writing was indeed "not quite as good as the year above" and allocated an extra period of English each week. While this did not make the children mature any faster, it did allow the English staff to concentrate in a consistent and focused fashion on teaching the techniques of good writing, says Ms McCartney.
"We used the methodology of the North Lanarkshire writing pack, which is aimed at 5-14 but very valuable right up to Higher.
"We analysed examples of good writing, looked at word choice, imagery, writing techniques. We discussed how they could make these part of their own work before they wrote and how well they had done so afterwards."
The result of this focus on writing emerged in the prelim results, which showed no significant difference between the writing performance of the S3 and S4 pupils.
On the other hand, the results for close reading did show the fourth years performing rather better than their younger colleagues. "It was an issue of maturity again, I think," says Ms McCartney.
"The third years have, since then, been catching up very quickly, and their close reading is improving faster than the fourth years'. Even in the last few days we've decided to present several more S3 kids at CreditGeneral level because they have come on so fast.
"I am cautiously optimistic that next week our third years will do just as well as our fourth years."
If this proves to be true, there will then be two years to tackle Higher, instead of the horribly pressurised two-term dash that pupils and teachers currently undertake.
"We are really looking forward to the luxury of taking the course at a slower pace, going into detail, consolidating skills.
"Right now it feels like you are trying to batter literature into them.
It's the philistine's view of Hamlet. It's why a lot of teachers have stopped doing the more meaty and demanding texts, like Shakespeare. We never had time to do them justice.
"This is going to be great."
Other departments at Dalziel High are now preparing to compress their S1 and S2 courses into one year, so that pupils will gain the benefits in these subjects too.
These are by no means confined to stretching the time available for post-Standard grade courses, says Pauline Allison, PT maths.
"We used to lose so many children's interest in S2 because of the amount of repetition they had to sit through. The difference in their motivation now is amazing. They are really interested because they are doing new stuff.
"It's what we are most pleased about. It makes the teaching easier and being in front of a class a much nicer experience. The kids want to learn, not just the top sections but right the way down. It's fantastic. We love it."
Another noticeable difference between the S3 Standard graders and their older colleagues, says Ms Allison, is their greater willingness to listen and learn.
"We saw that in particular with the biggest challenge they faced: problem solving. From the start in S2 our monitoring showed this wasn't good. We hoped it might improve as they got more familiar with the course but it didn't."
Reading a problem and translating words into maths is not easy at any age.
But what made this a serious issue for these pupils, says Ms Allison, was their reluctance even to make a start in case they got it wrong.
"So we had to get them away from that, tell them to have a go even if they weren't sure where they were going. It was one part of working on their exam technique which none of these kids had done before. They responded very well."
As with English, remedial action was rewarded with steady improvement in pupil performance. The S3 Standard graders' problem-solving still lagged behind last November, but by the time of the second maths prelim in March they had fully caught up with their S4 colleagues.
Mr Miller anticipates a few organisational problems in extending S3 Standard grades to other departments, but says: "Maths and English have paved the way. We will use the same methods, the same close monitoring and comparison of results. We will find the weaknesses and overcome them.
"The benefits of doing Standard grade at S2 to S3, then Higher Still at S4 to S6, are so great that I believe the majority of schools in Scotland will be doing this in five years' time."