51.6.2 Focusing on Similarities and Differences Between
Concepts and Phenomena
In science teaching, many teachers emphasise the importance of taking one thing at
a time and thus reduce the complexity, which is especially common in science
education. On example might be that in order to understand the greenhouse effect
you need to know about the gas carbon dioxide and how the gas is created in a car.
Normally, students are taught about the gas carbon dioxidefirst and then, often
much later, about the green house effect. The same applies to atoms and ions.
Normally atoms are taught in year six and ions in year eight. This view was
challenged in the students’reflections as they highlighted that the meaning of
phenomena to a large extent is determined by how the specific phenomena differ
from another phenomena (e.g. the difference between an atom and an ion). Several
of the students emphasised that they found it easier to understand the science
concepts when the teacher specifically focused on the similarities and differences
between concepts instead of presenting the concepts alone.
Student 3: Well now he compares the different concepts.
Student 2: You can clearly see the differences and similarities.
Student 1: Yes, you see concretely what belongs to what and what differs the concepts from
each other.
Student 3: Yes, it’s great when he contrasts the two...like what are the differences between
recessive and dominant genes?Consequently, for a teacher it may be better to contrast things with each other and
focusing on the differences between them, than to take them one at a time. Instead
offirst teaching about the atom, then introducing the molecule and then the ion to
help studentsfinally understand what happens within a chemical reaction between
sodium and chloride, these can be taught together at the same time, focusing on the
similarities and differences between the concepts. The students also highlighted that
the way the teacher carefully chose his examples also helped them in their learning.
Student 1: In this lesson we talk about eye colour and he (teacher) explains how the colour
appears. It is good that he keeps up to one aspect and follows the common thread and that
he does not start to talk about plenty of different characteristics. Then he will probably loose
us.As was indicated, the students’emphasised that the way the teacher organised the
content within his teaching made difference for how the content was understood,
hence an important aspect of PCK.
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