It failed to reach the leaves and fell into the test tube.
Undaunted, he rammed his finger in, hoping to dislodge the pencil, and finally came for assistance with his finger stuck inside the tube.
The point of this story is that a concrete thinker like Charles was so baffled by the procedures of the experiment that he failed to engage with the concept. It made me realise that there are many issues which can become barriers to understanding.
The HMIE report Improving Achievement in Science in Primary and Secondary Schools 2005 and the Scottish Executive's A Curriculum for Excellence both seem to argue for change to produce more balanced and effective young citizens for the 21st century.
Some think that to challenge children and raise attainment in S2, we should introduce certificated courses at that stage to prepare pupils better for Higher examinations. This is, I believe, wrong.
In terms of child development, younger children will be less equipped to deal with the scientific concepts. Using a Piagetian model, a greater proportion of the children (perhaps as few as 20 per cent) will not yet be "formal reasoners" capable of understanding scientific theories.
I believe this process is likely to have children studying courses at a lower level than they would be capable of at a later stage.
Michael Shayer's most recent finding (in the British Journal of Educational Psychology) is that children's cognitive ability at 11 to 12 has fallen over the past 15 years by almost the equivalent of a year of brain development.
Some argue that national results show improvements in children's attainment. I think any teacher who has taught children over the past 20 years would concur with Mr Shayer's findings.
How do we explain these apparently contradictory statements? By reference to research from around the world which shows that, when the stakes are high, teachers teach to the tests, which produces a short-term, three-year uplift in results before they plateau.
The aspirational Curriculum for Excellence programme intends to meet the needs of modern society. But how do teachers deliver those aspirations?
Working with the cognitive acceleration in science education (CASE) programme, the King's College London science process and concept exploration (SPACE) project on misconceptions in science, and subsequently Let's Think and Let's think through Science, helped me understand. These programmes help child development through intervention lessons with specific challenges, but I believe the future lies in the constructivist approach.
P4 children, working with the concept of conservation, were comparing the same amount of water transferred from beaker to cup: were they different? Why?
They responded: "The cup held more water because the level was higher than in the beaker" and "Cup smaller at the bottom so water is less spread out in cup".
One girl put the cup inside the beaker and observed that there was space between the cup and beaker. I squeezed the cup and asked if the cup now had more. She said: "No, 'cos it's being squeezed up and when you don't squeeze it the water goes back to the same."
This "group brain" approach helped the children to change their views and understand, with the teacher having a guiding role.
Mr Shayer's research shows far fewer children understand these simple concepts than in previous generations. So we need to engage them in more concrete experiences to explore and develop understanding of these fundamental ideas.
The types of science lesson that appear from research to produce big effects on learning are those which get children to work in groups. Another key factor for learning is metacognition. In this phase of the lesson, children talk about the process of how they have learned, reflecting on the aspects of the lesson, strategies they and others tried and comparing and contrasting them.
I believe this process is fundamental to the development of the learner.
It's why these different approaches have such large effects on children's reasoning.
These teaching skills need effective CPD for staff. Scotland needs Science Learning Centres that would plan future CPD programmes, monitor quality and act as resource centres.
Tom Dickson is an advisory teacher in Fife