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UNESCOModule 12: Wood as a structural material - Teacher's Notes
Wood as a structural material
Teacher's Notes
Introduction
In this module, students are asked to:
• interpret visually presented data about the structure and growth of wood;
• plan and carry out comparisons of stiffness and strength using the simple
apparatus with which they are provided;
• interpret data on the stiffness and strength of wood and steel and relate this
to their densities;
• apply information about why the moisture content of wood varies and how
this affects wood in practical situations;
• compare the swelling/shrinking of different types of wood due to changes in
humidity.
Scientific Be technological concepts
• grain;
• cells;
• stiffness;
• strength;
• density;
• sap;
• humidity.
Teaching approaches
The module begins by providing students with the opportunity to relate the fact
that wood has a grain to its microscopic structure. Details of the microscopic
structure are also related to the growth pattern of wood. Students then plan and
carry out tests: firstly to compare the stiffness of wood and plastic; secondly, to
compare the strength of wood along and across the grain and to relate this to the
structure of wood. Data is also provided to enable students to compare the
strength and stiffness of wood compared to steel in relation to their densities.
Finally, students are given information about the seasoning of wood and data
about how seasoned wood swells and shrinks with changes in humidity. These
ideas are then applied to practical contexts and students are also asked to
compare the amount of swelling/ shrinking in different types of wood.
Notes on the activities
Page 1: It is recommended that students examine actual specimens of wood
and count the annual rings in actual cross-sections of trees as well as interpreting
the diagrams provided. Students could also look at microscope slides of wood in
both longitudinal section and cross-section.
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