Topic: What causes the disintegration of rocks, called weathering?

Addressee

1st class of high school or technical high school students (basic scope)

Core curriculum

V. Litosphere: relationship between the interior structure of the Earth and the tectonics of lithosphere plates, internal and external processes shaping the Earth's surface and their effects, rocks.

Student:

3) characterizes the main external processes modeling the Earth's surface (erosion, transport, accumulation) and effects of the sculptural activity of rivers, wind, glaciers, glacier and seas and weathering;

General aim of education

The student will learn about the weathering process and its effects.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• exchange and discuss types of rock weathering;

• give examples of rock forms created as a result of the weathering process;

• explain what the process of killing is about.

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;

• interactive whiteboard, tablets/computers.

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.

Introduction

• The teacher gives the topic, the goals of the lesson in a language understandable for the student, and the criteria of success.

• The teacher plays the abstract recording for all students. Participants listen carefully and give feedback on the difficulty of the text being heard using the traffic light method. Students are provided with green, yellow and red cards. While listening to the recording, they display the appropriate color for self‑assessment and to inform the teacher:
  green - I'm fine, I understand everything;
  yellow - I have some doubts;
  red - I do not understand anything, please help.
  The teacher responds depending on the needs of the students, deciding to repeat the recording, listen to the recording while following the text or translate the text.

Realization

• The teacher explains to students the concept of „airing” and discusses its types: physical airing; chemical weathering; biological weathering.

• Students independently or in pairs solve an interactive exercise, which aims to systematize and organize information on processes leading to the breakdown of rocks.

• The teacher initiates a discussion about the process of kenation and well‑known karst forms (in Poland and abroad) and their natural values.

• Work of the whole class team. Students stand in a circle. The teacher encourages them to play: throws a ball or mascot to one of the students, saying the English word or notion learned in the lesson. The student gives the Polish equivalent, mentions another word in English and throws a ball or mascot to a friend or colleague.

Summary

• The teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

• The teacher asks the students questions:

  • What did you find important and interesting in class?

  • What was easy and what was difficult?

  • How can you use the knowledge and skills you have gained today?

  Willing/selected students summarize the lesson.

Homework

• The teacher asks interested pupils an optional homework, which consists in conducting independent experiments presented at the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

What causes the disintegration of rocks, called weathering?

The process of disintegration of rocks leading to changes in their chemical or physical properties is called weathering. The rock material that is the product of this process is eluvium. Three types of rock weathering have been distinguished taking into account the factors causing the process of weathering and the nature of changes occurring in the rocks.

Physical weathering, also known as mechanical weathering, occurs when rocks disintegrate into smaller pieces under the influence of:

• repeated temperature changes,

• changes in the volume of freezing water,

• increase in the volume of silty rocks after they have been soaked in water,

• growth of crystals in crevices.

During this process, the chemical composition of the rock does not change. Rubble composed of large blocks of rock formed by physical weathering is called a stone run.

Chemical weathering occurs when rocks undergo changes in terms of their chemical composition, mineralogical composition, cohesiveness, or state of aggregation. Such processes occur under the influence of:

• dissolution,

• hydration,

• oxidation,

• other chemical reactions.

The group of the forms created as a result of the influence of even slightly acidified water on soluble rocks (especially carbonate rocks) is called karst. This is an example of chemical weathering.

The karstification process consists in: the dissolving and washing away of carbonate rocks (limestones, dolomites, gypsum, chalk, rock‑salt and others) by waters which contain carbon dioxide, the widening of crevices and cracks in the rock, as well as the precipitating of calcium compounds (mainly aragonite and calcite) and depositing them on the surface of the rock in the form of dripstones.

Biological weathering is caused by the mechanical or chemical impact of living organisms on rocks. Some examples of mechanical fragmentation of rocks are:

• growth of plant roots,

• growth of plant shoots,

• swelling of germinating seeds,

• digging of burrows by animals.

The chemical variation of biological weathering is the decomposition of rocks as an effect of:

• acids and other chemical compounds produced by plants,

• various chemical compounds produced by fungi,

• chemical compounds produced by animals,

• chemical substances resulting from the decomposition of dead remains of organisms.

• Under the influence of external factors, rocks change their chemical and physical properties.

• Depending on the prevailing factors, we distinguish the following types of weathering: physical, chemical, and biological.