Topic: The circulation of matter and flow of energy in nature

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

8th‑grade students of elementary school

Core curriculum

Grade VIII – biology

VII. Ecology and environmental protection. Pupil:

5) presents the trophic structure of the ecosystem, distinguishes producers, consumers (I and further rows) and destructors, and presents their role in the circulation of matter and energy flow through the ecosystem.

General aim of education

Students present the role of organisms in the circulation of matter and the flow of energy in the ecosystem.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to describe the flow of matter in nature;

• describe the flow of energy in nature.

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;

• jar with lid;

• rocks;

• potting soil;

• several small plants;

• model or drawing of the Sun.;

• cards with names of individual links in the food chain;

• bar of chocolate.

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

Realization

• The teacher asks pupils to read the passage entitled „The circulation of matter in nature”. Then it displays a picture of the miniekosystem in a bottle (eg, found in the resources of the Internet) and asks the pupils if the miniekosystem presented in the photograph can function in a closure. The teacher talks with students in such a way as to direct their attention to the issue of the circulation of matter.

• Participants familiarize themselves with the content presented in the interactive illustration. Then the teacher discusses the issues with the students.

• Students read the fragment „Flow of energy in nature” and analyze the illustration with the same title. Volunteers draw cards with the names of individual links in the food chain and form its model: they set themselves in the right order with respect to each other and to the Sun. The teacher asks students which link in the food chain produces sugar, which is the source of energy material. After the students have indicated the volunteer playing the role of the producer, the teacher hands him a row of chocolate with the number of cubes that correspond to the number of links in the food chain model created by the students. Now each „link” breaks one ankle one by one (preserving the order of the „chain”) and eats it. The teacher asks students to answer the question: „What happens to energy in nature?”.

• Students read the fragment „Flow of energy in nature” and analyze the illustration with the same title. Volunteers draw cards with the names of individual links in the food chain and form its model: they set themselves in the right order with respect to each other and to the Sun. The teacher asks students which link in the food chain produces sugar, which is the source of energy material. After the students have indicated the volunteer playing the role of the producer, the teacher hands him a row of chocolate with the number of cubes that correspond to the number of links in the food chain model created by the students. Now each „link” breaks one ankle one by one (preserving the order of the „chain”) and eats it. The teacher asks students to answer the question: „What happens to energy in nature?”.

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

Summary

• The teacher asks students to evaluate the classes using the „Smily” method.

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

The circulation of matter and flow of energy in nature

Matter is the term that encompasses all known substances. Matter is what plants, animals, humans and the environment are made of. Matter in nature doesn’t increase or decrease. Instead, it is in constant circulation. As you already know, simple compounds (e.g. water, carbon dioxide or mineral salts) are assimilated by primary producers in the photosynthesis process. They are used to produce protein, sugars and fats that make up a plant. When a plant is eaten, these compounds are used by herbivores – first‑order consumers – to sustain their bodies. A part of matter is excreted, e.g. in the form of simple inorganic compounds, such as water and carbon dioxide in the breathing process. Predators – second‑order consumers – eat herbivores and assimilate that matter in turn. After the death of each organism, its body is eaten by decomposers who decompose it into simple compounds. These in turn are used by primary producers and the circle is closed.

Energy flows in parallel to the circulation of matter in ecosystems. The volume of matter in circulation is constant and after various transformations still remains in the ecosystem. Energy, on the other hand, must be introduced into the system from outside and gradually dissipates. The vast majority of energy comes from the Sun.
Plants use luminous energy and store it in chemical compounds. They use a considerable part of this energy to grow their bodies, produce flowers, fruit and seeds. That’s why only part of the energy is transferred to first‑order consumers. Herbivores also use a considerable part of energy from food to sustain their own life functions (movement, body heat, food acquisition, breathing, breeding, etc.). Only a part of that energy is stored and transferred to predators. When the remains and excrements of primary producers and consumers are finally decomposed by decomposers, the rest of energy contained in chemical compounds is released. Once energy has been used, it cannot be re‑used. That’s why it’s said that, in nature, matter circulates while energy flows. The primary source of energy for all life processes on Earth is the Sun.

• The matter of inorganic form (water, carbon dioxide, mineral salts) changes into an organic form (sugars, proteins, fats - present in the bodies of plants and animals), finally becomes inorganic matter oncle again (result of destructors on organic compounds).

• The energy flows from the sun, through the bodies of plants, animals and people, and at each stage is partly used and partly dispersed.