ETV “Junior Secondary Science” Programme
Grouping and Classifying Things
Teachers’ Notes
Target Audience
Secondary 1 - 3
Duration
20 minutes
Production Aim
This programme is a teaching resource produced especially for enriching the
classroom teaching of the Syllabus for Science (Secondary 1 – 3) prepared by the
Curriculum Development Council (1998).
The content of the programme serves to illustrate the following part of the
Syllabus：
“Unit 2 – Looking at Living Things
Topic 2.4 Sorting things into groups”
Key Points
1.
2.
3.
An introduction to the principles of grouping and classifying things.
A brief introduction to the major grouping categories of living things.
An introduction to the principle and technique of construction and using
keys for identifying living things.
Content Outline
This programme is divisible into 6 segments as follows:
1. Introduction
With reference to people and other daily examples, the audience is led to
understand the need for simplifying the descriptions of things.
2. Grouping things
An illustration of how grouping things into units and giving each unit a name can
much facilitate our communication. The audience is briefed of the principle of
grouping things by similarity.
3. Classifying things
The audience is show the way of dividing a group of things into subsets by the
principle of classifying things by difference.
4. Classifying plants
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Based on the ability to produce flowers, plants are broadly divided into two
major categories: flowering plants (plants capable of producing flowers) and
non-flowering plants (plants incapable of producing flowers).
With reference to the body of a Chinese balsam, the audience is shown that the
body of a flowering plant typically consists of roots, the stem, leaves, flowers,
fruits and seeds.
A brief introduction to the major groups of non-flowering plants, including algae,
bryophytes (mosses and liverworts), ferns and gymnosperms. The typical
characteristics of each group are highlighted and examples are shown.
5. Classifying animals
The concepts of backbones and the vertebral column are clarified. Based on the
the presence or absence of a vertebral column inside the body, animals are broadly
divided into two major categories: vertebrates (animals with backbones) and
invertebrates (animals without backbones).
The characteristics and common examples of each of the five major groups of
vertebrates, namely, fishes, amphibians, reptiles, birds and mammals are
highlighted.
The audience is then shown the characteristics and common examples of each of
the following groups of invertebrates, namely, molluscs, jointed-legged animals,
insects, spiders and crabs.
6. Keys
A narration of the way to construct a dichotomous key (or forked key) based on
the shape and structure of a collection of living things. The audience is also shown
the way to identify a fish by following the descriptions of a relevant key.
Suggestions for Utilization
1. The teacher is advised to show the programme in two lessons.
In the first lesson, the teacher may show segments 1 to 5 of the programme so as
to supplement the teaching of the following key points and contents of the CDC
S1-3 Science Syllabus:
Key Points – Classification; Animals with and without backbones; Flowering
and non-flowering plants.
Core Content – Classifying animals into those with and without backbones;
Classifying plants into flowering and non-flowering plants.
Extension Content – Classifying animals with backbones into fishes,
amphibians, reptiles, birds and mammals.
In the second lesson, the teacher may show segment 6 of the programme so as to
supplement the teaching of the following key point and contents of the CDC S1-3
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Science Syllabus:
Key Point – Keys.
Core Content – Use of simple keys for identification.
Extension Content – Constructing simple keys for identification.
2. For better utilization, the teacher may spend 5 to 10 minutes at the beginning of
each lesson to lead students to discuss with reference to the Preparation before
viewing the programme part of the Suggested Activities. The teacher may then
show the programme. After the show, the teacher may spend another 10 to 15
minutes to discuss with students with a view to consolidating the concepts and
methods illustrated in the programme. The teacher is advised to refer to the
Activities after viewing the programme part of Suggested Activities.
Suggested Activities
(The following activities are suggested for teacher’s reference only. The teacher
may wish to use the activities according to students’ abilities, the learning
environment of the class, and the teaching time available.)
Preparation before viewing the programme
The teacher may show to students a few animal or plant specimens and related
field guides published by the former Urban Council, and advise students to find out
the name of each specimen. The teacher may then ask students how they get the
names. The teacher needs not comment on students’ answers before showing the
programme.
Activities after viewing the programme
1. The teacher may invite students to apply the method illustrated in the programme
to identify the animal/plant specimens with reference to the keys included in the
Urban Council field guides.
2. The teacher may follow on the question posed in the programme: “How to
construct a key for a spider, a crab, an ant and a butterfly, beginning with the
number of eyes?” (Suggested answer is shown in the key on page 4)
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A key for identification of jointed-legged animals
spider, crab, ant, butterfly
with 1 pair of eyes
with more than 1 pair of eyes
spider
with wings
without wings
butterfly
bearing 6 legs
not bearing 6 legs
ant
crab
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