Topic: Mosses

Author: Elżbieta Szedzianis

Target group
5th grade students of an eight‑year elementary school

Core curriculum

5. Diversity and unity of plants.

2) Mosses - student:

a) conducts an observation of moss representatives (photos, engravings, live specimens) and presents the features of their external construction,

b) identifies an unknown organism as a representative of mosses based on the presence of characteristic features,

c) explains the importance of mosses in nature; plans and conducts an experiment to demonstrate the ability of moss to absorb water;

Lesson aim

The students describe the structure and their role in nature and as a pioneering species.

Key Success Criteria

• you will observe and name the parts of a moss,

• based on the observation of the moss, you will be able to explain, what its role in the environment is,

• you will formulate a research problem and conclusions on the pioneering role of mosses in nature.

Key competences

• communicating in a foreign language;

• communicating in the mother tongue;

• mathematical competence and basic competences in science and technology; 

• learning to learn;

Methods/forms of work:

Class talk, brainstorming, laboratory method, work with text.

Individual work, group work.

Teaching measures:

• abstract;

• interactive whiteboard or traditional blackboard;

• tablets/computers;

• dried moss turf;

• magnifying glasses;

• scales

• dish with water;

• developing dish or a sheet of white paper.

Lesson plan overview (Process)

Introduction

1. The teacher shows a photograph on which you can see mosses and grass. He asks the students to:

• name the plants they see on the photograph,

• to compare the ground on which grass and mosses visible on the photo grow,

• to enumerate the differences between grass and mosses.

2. The teacher explains that the heroes of today’s lesson are going to be mosses. He gives the topic of the lesson and the key success criteria of the student.

Realization

1. The teacher asks the students to look through Gallery 1 (or other graphic source) and write down in their notebook what the environment in which mosses live is. The teacher emphasises the fact that certain mosses can grow on walls and rocks which do not soak any water and have no soil. He then asks the students to take those facts into consideration and form a research problem that refers to the ability the mosses have to grow in an unfavorable environment.

2. They then attempt to formulate these problems. The proposals are written down on the board, in accordance with the brainstorming method. After completing the list, the students select the best research problem, and give hypotheses connected with the subject.

3. One of the hypotheses concerns the mosses ability to cumulate water. In order to verify it, the students are divided into groups of four and they observe the dried moss turf. They have access to magnifying glass and scales, a dish with water and a developing dish or a sheet of white paper. They work on the tasks in the work sheet. First, they extract single plants from the clump, look at their build and compare it with the illustration in the abstract. The show and name the parts of the plant, then they solve the interactive task number 1.

4. Next, they weigh the moss clump and they put the clump into the dish with water for a few minutes.
   After a while, they take out the moss out of the water, shake the droplets off and weigh it again. They also check the pH of the soil at the bottom of the moss bunch. They write down their observations in the work sheet.

5. Then they use the abstract to learn about the functions of the different organs of the moss and solve task 2.

6. They conduct Observation 1 and write down their observations and results.

7. Second hypothesis concerns the ability mosses have to create their own ground. The teacher explains that it is composed of dead elements of mosses and fragmented rocks. He also explains that mosses destroy rocks by producing acids that lead to their decomposition. The teachers mentions that the presence of the acid can be detected using universal indicator and explains how to use it. The students use the universal indicator to describe the pH of the water before they put the moss in it.

Summary

1. The teacher asks the students to explain, why mosses can live on rocks and walls. He asks the students to formulate conclusions and write them down in their work sheets. The teacher points the suggestions of the students so that the conclusion becomes cohesive with the hypotheses and includes the solution to the problem

2. The teacher asks the students to finish the sentences:

During this lesson, I found out....

During this lesson, I have learned...

Optional homework

Answer the following question with one sentence: What is the role of mosses in the environment?

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Mosses

Mosses are small plants that form dense clusters looking like soft cushions, the so‑called turfs. Just as algae, they are autotrophic organisms that need water, mineral salts, carbon dioxide and light to be able to live. They are characterized by resistance to prolonged drought. A compact group of these plants can accumulate large amounts of water in numerous narrow spaces between individuals and parts of their bodies. When the ground around dries out, mosses still function well. Even when completely dried out and seemingly dead, they may continue their life processes after rehydration.

Mosses are characterized by a simpler structure than other terrestrial plants. Instead of roots they have rhizoids, instead of stems – stemlike structures, and instead of leaves – leaflike structures. With the use of such names, biologists inform that these organs are only to some extent similar to leaves and stems of vascular plants. They do not have a specialized tissue that conducts water and nutrients between particular parts of the plant. They have no covering tissue, so they can absorb water through the leaflike structures. Despite all, such organ structure allows including mosses in embryophytes. They reproduce sexually and asexually through spores.

Common Haircap grows in wet forests and meadows. It occurs in groups, forming a fluffy turf. It can be found all over Poland. It is quite large, it reaches up to 30 cm in height. Its above‑ground part is a straight or branched stemlike structure with leaflike structures. Small, green leaflike structures conduct photosynthesis, absorb and store water. It absorbs it using its entire surface from humid air, rain or dew. When it dries, it curls and sticks tightly to the stemlike structure, which reduces the surface through which the plant can evaporate water. Thin, threadlike rhizoids grow from the bottom of the stemlike structure. They serve the plant to keep it in the ground. In summer, at the top of a leafy stemlike structure grows a stalk – long, with no chlorophyll and topped with a sporangium. Small spores are formed therein. When the air is dry, sporangium cells contract, resulting in its operculum falling off and spores being released. They are spread by the wind – the farther away, the higher the sporangium is located.

Like lichens, mosses living on rocks, dunes and other inaccessible places contribute to soil formation. Their dead remains enrich the substrate with humus, preparing it for more demanding plants. Thanks to their presence, rainwater does not flow directly to rivers on the ground, but is stored in turfs. This way, mosses protect against a rapid rise in the level of water in rivers, which reduces the threat of flooding. The compact turf of these plants also protects the soil against erosion (leaching by rainwater, wind blowing). The layer of mosses and litter is the living environment of a huge number of protozoa, fungi and invertebrate animals (snails, insects, spiders) and small vertebrates (frogs, lizards, rodents).

Peat has numerous applications in horticulture and agriculture, medicine and cosmetics. Crumbled peat mixed with water creates mud used for warming compresses and baths with anti‑inflammatory and bactericidal properties.

• Mosses abundantly occur in humid land environments.

• They are spore plants classified as embryophytes.

• Mosses are formed from a stemlike structure on which sex organs (gametangia) are located, and a leafless stalk on which sporangium develops.

• Mosses regulate the circulation of water in the environment, they are a shelter and food for animals.

• Peat is used in medicine, gardening and as a source of fuel.