Topic: Root

Target group

5th grade students of an eight‑year elementary school

Core curriculum

5 ) Angiosperms. Student:

b) observes the angiosperms (photographs, engravings, live specimens); recognizes their organs and determines their functions (root, stem, leaf, flower);

c) describes modifications of roots, stems and leaves as adaptation of angiosperms to life in specific environments;

d) presents methods of vegetative reproduction of plants and observes selected methods of vegetative reproduction.

Lesson aim

The students describe, based on their observations, the build of the root and how it adapted to perform life functions.

Key Success Criteria

• you will learn the difference between fibrous roots and taproots,

• you will draw and describe a schematic outline of a young sunflower plant,

• you will describe, how the root of a sunflower and horseradish adapted to serve their functions.

Key competences

• communicating in a foreign language;

• mathematical competence and basic competences in science and technology; 

• learning to learn;

Methods/forms of work:

Problem strategy; observation, speech, workshops - solving problems.

Individual.

Teaching measures:

• abstract;

• interactive whiteboard or traditional blackboard;

• tablets/computers;

• cultivation of wheat/oat and sunflower;

• magnifying glasses;

• horseradish roots;

• ivy sprouts with adventitious roots;

• a pot with soil;

• sheets of paper of different colour to assess the knowledge gained during class.

Lesson plan overview (Process)

A week/10 days before the class, the students were supposed to start a cultivation of wheat/oats and sunflower, and bring them for this class.

Introduction

1. The teacher gives the topic of the lesson, explains to the students, using accessible language, the aim of the lesson, and shows them the success criteria.

2. The teacher asks the students: which part of the body of a plant appeared first while the plant was sprouting? Why exactly this one? The students propose their hypotheses. They are written down on the board and then, one hypothesis is selected to be investigated during class.

3. The teacher informs the students that, based on the observation of the growing plants, they will solve the problem.

Realization

1. The teaccher asks the students to look at single plants from their cultivation and identify their organs using Illustratio 1, and then to draw them (applying the rules of showing biological objects on a schematic drawings). The schematic drawings should be described and signed. Using Illustration 2 they can determine, what kind of root system these plants have, and include that type of information while describing the schematic drawing.

2. The teacher emphasises the fact that during describing and talking about plants both he and the students used the word ‘organ’. He asks the students to say, what in their opinion the organ of the plant is. Next, the students read a definition of an organ from a dictionary and they explain, why a root is considered an organ. They write down the explanation in their notebooks.

3. The students observe and, while solving theoretical tasks, verify the hypothesis that was formulated at the initial stage of the lesson.
The students describe using a magnifying glass the trichomes of the root and orally describe them.
They complete the following exercises and describe the functions of the trichomes and the roots.

a. Think whether trichomes are better compared to fur or a hairy towel.
b. The roots of certain plants reach very deep. Alfalfa, for example, has sprouts that can be betweem 0.3 - 1 m height, and the grow between 3 - 10 meters inside the ground. What are the functions of the roots?
c. The surface of all the roots of one plant of rye has around 700 square meters, and the surface of its sprout is just around 1 square meter. What are the functions of the roots?

The students should refer to the absorbent surface off the root and its ability to anchor the plant to the ground. Next, they should write down (based on their findings) in one sentence the information about these functions of the root (absorbing water, anchoring the plant to the ground).

4. The teacher presents storage roots of a horseradish and an adventitious root of an ivy, as well as shows ivy on the board (Gallery 1). He asks the students to define additional functions of roots based on this. Then, he divides a horseradish root into 3 parts and plants them in a pot. He asks the students how many progeny plants they expect. The cultivation is signed, the date it was started is written down and then, it is placed on the window sill.

Summary

1. The teacher asks what features of the root have to be taken into consideration in order to identify the functions a root has.

2. He asks the students to enumerate factors how the roots adapted to the environment they live in.

3. Next, the students complete the interactive task 1.

4. Using sheets of color paper (red, yellow, green), the students assess, whether they achieved success during the class.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Root

Plants that currently dominate on land are embryophytes, i.e., autotrophic organisms made of tissues and organs. Among them, the most numerous group is vascular plants, which in the conducting tissue have specialized cells that are responsible for conducting water - vessels. Most of them produce seeds hidden in the fruit, which is why they are called angiosperms, the therm that comes form the Greek words angeion („case” or „casing”) and sperma („seed”).

An organ is a part of a plant organism with a characteristic structure and a specific function. Vascular plants form underground and above‑ground organs. The former include the root, and the latter - the stem, leaves, flower and fruit. An efficient cooperation of all organs allows the plant to function properly and reproduce.

The root is an underground plant organ that keeps it in the soil and collects water along with mineral salts from the ground. Complexes of many roots in one individual are called root systems. In seed plants there are distinguished two types of root systems: taproots and fibrous roots. In plants that have the taproot system there is a long main root from which many shorter and finer branch roots derive. Such an extended system can reach deep into the ground. Other plants form dense fibrous systems consisting of a bundle of numerous roots growing from the lower part of the shoot. They are similar in thickness and length, they can branch out. They occupy a significant area - the greater it is, the larger the plant. Well‑developed root systems are conducive to a more efficient collection of water accumulated in the soil.

In the external structure of the root there are several sections called zones. These are: root cap, meristematic zone, elongation zone, root hair zone and lateral root zone. Individual zones appear successively as the root grows. Each zone has a different structure and a different task in the root. Each lateral root in the taproot system consists of the same zones as the main root.

In addition to their basic functions, i.e. keeping the plant in the soil and absorbing substances out of it, roots can also perform additional functions. In this case, they have some characteristic structure features. Roots that perform additional functions are defined as modified or transformed. Among the most common root modifications there are special adaptations to collecting food, taking oxygen, supporting the plant with flexible stems on supports, producing additional supports that keep the plant in the ground. Roots that grow from the stem or leaves are called adventitious roots. They can support or replace the main root.

Types of modified or transformed roots:

• storage roots are thickened and develop as a result of expansion of the storage parenchyma inside the root; plants store large amounts of nutrients there, which they use in spring to produce new shoots; such roots are found in carrots and beets;

• climbing roots grow from the stems of climbing plants and creeping plants; they allow the plants to attach themselves to supports in the form of branches or tree trunks, and strive upwards in search of light; they can be found in such plants as ivy, Virginia creeper;

• The root keeps the plant in the soil and absorbs water with mineral salts from the soil, and in some plants it stores spare substances.

• There are two types of root systems: fibrous – occurring, for example, in grasses, and taproot - found in trees.

• In the external root structure, the root cap, the meristematic zone, the elongation zone, the root hair zone, and the lateral roots zone are distinguished.

• The roots undergo modifications which adapt the plants to the conditions of the environment in which they grow.