Topic: Temperature‑related expansion of gases

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

Core curriculum

7th‑grande 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 thermal expansion of gases

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• explain phenomenon of thermal extension of gases;

• desing experiment illustrating thermal extension of gases.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• 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;

• sheets of gray paper.

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

• The student performs the experience from Task 1 in the abstract.

Introduction

• The teacher asks the chosen student to explain what the thermal expansion of the substance consists in and why it is safer to pour hot water into a glass‑proof dish than to a normal glass.

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

Realization

• The teacher asks students to familiarize themselves with the content of the abstract. Then he divides the class into teams (five or six) and recommends the task: „Think of how to inflate a rubber balloon using the bottle, water and heater to reach its largest possible size. Submit your proposal on the poster „.

• Students carry out the task, and after a specified time they post posters. A representative of each group discusses the idea of the team.

• The teacher shows the question on the board: „What will happen to the filled balloons if we put them in the temperature of about -196°C, and then we will take them out and leave them on the table in the room?” Students, working in groups, consider the possible effects of the experiment and write the answer.

• The lecturer discusses with the students the experience they have made at home. The teacher points the person who shares his insights and explains the conclusions made.

Summary

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

• The teacher invites students to the evening show of letting go of Chinese lanterns.

Homework

• Develop a lap book containing issues learned during the lesson and bring your work to the next class.

• 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

Temperature‑related expansion of gases

The phenomenon of temperature‑related expansion is best visible in gases. This is due to their structure – their molecules move very fast. Heat makes this movement even faster, pushing molecules further apart from each other.

If we fill a balloon with gas on a cold day and then take it to a warm room, there is a risk that the balloon will break. Why? The gas contained in the balloon will expand with increasing temperature. If the balloon has already been inflated tightly, it may break.

How can we use the phenomenon of temperature‑related expansion of gases? For example, in balloon flights. Heated air increases its volume and is lighter than cold air surrounding the balloon. A hot air balloon rises because the air inside is expanded and weighs less as a result.

• 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.