Topic: Thermal expansion of solids

Supplementary material for use in lessons in the group of natural sciences (nature, biology, chemistry, geography, physics), additional classes, science clubs. It can serve as a resource for expanding knowledge, preparing students for science competitions.

Target group:

7th‑grade students of elementary school (physics).

Core curriculum

7th‑grade of elementary school – physics

IV. Thermal phenomena. Student:

5) analyzes qualitatively the relationship between temperature and average kinetic energy (chaotic motion) of molecules.

General aim of education

Students demonstrate the thermal expansion of solid bodies

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to explain what thermal expansion of solids is;

• to carry out an experiment demonstrating thermal expansion of solids;

• provide examples of how thermal expansion can be used in the construction industry.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• mini flip charts.

Lesson plan overview

Before classes

• Students carry out the „Experience 1” at home. His course is documented by making a film, which is sent to the teacher's e‑mail address on the date set by him. The film should present only the experiment carried out, not the people participating in it.

Introduction

• The teacher asks the chosen student to explain what the thermal expansion of the substance is based on, for example, gases and liquids..

• The teacher explains the aim of the lesson and together with students determines the success criteria to be achieved.

Realization

• The teacher presents two films made by students. He does not reveal the names of the authors. One of the films is prepared in accordance with the instructions, and the presented experience is carried out flawlessly or with minor defects. The second has the most errors. Students write down feedback on the authors of both films. The teacher collects the cards, and after the lesson hands them to the authors.

• The lecturer announces the film „Egg in a Jar”. He instructs his pupils to write a research question and a hypothesis in the form provided in the abstract. Then it displays the video and the students record their observations and conclusions. The teacher indicates the person who shares his insights and explains the reasonableness of the conclusions he has made.

• The teacher asks students to look for examples in the abstract of the use of thermal expansion of solids in construction..

Summary

• The teacher asks students to carry out the recommended interactive exercise themselves.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Thermal expansion of solids

As you already know, solids have a definite shape and a definite volume. A solid does not easily change its shape or its volume. Does this mean that they are not subject to thermal expansion? Let’s find out by performing an experiment.

Solids change their volume due to changes in their temperature. This phenomenon is much more visible in the case of metals. In the table below you will find some examples, if the length of the objects, which measure 1 m, are changed and are made of different materials, if we raise the temperature by 50°C.

The phenomenon of thermal expansion has a huge impact on our lives. Engineers have to take it into account when designing buildings and all metal structures: bridges, railway tracks or high‑voltage cables, as well as metal constructions of some buildings.

• Thermal (temperature‑induced) expansion is a change in the volume of bodies due to a change in their temperature.

• Thermal expansion of bodies is associated with an increased velocity of molecules and a rise in temperature.

• Gases expand the most while being heated, but the phenomenon of thermal expansion occurs in liquids and solids too.

• The phenomenon of thermal expansion must be taken into account when designing buildings and equipment.