Notes of Lessons: Biology, Class IV

[We have thought that it might be of use to our readers (in their own families) to publish from month to month during the current year, Notes of Lessons prepared by students of the House of Education for the pupils of the Practising School. We should like to say, however, that such a Lesson is never given as a tour de force, but is always an illustration or an expansion of some part of the children’s regular studies (in the Parents’ Review School), some passage in one or other of their school books.—Ed.]

Subject: Fertilization • Group: Science • Class IV • Time: 30 minutes

By E. M. Brookes
The Parents’ Review, 1903, pp. 547-548

Objects

I. To continue the lesson on pollination O_____ had last Monday.

II. To help her to understand better the method of growth of a plant by taking in detail the growth of one portion of its structure.

III. To show her that botany is the study of the life of a plant, not merely an examination of its structure.

Lesson

Step I.—Ask O_____ what kind of organs a stem bears. A pistil of carpels is made up of carpellary leaves. Give a well-developed pistil to be dissected and show model of a pistil.

Step II.—An ovary bears ovules; ovules become seeds. How? By fertilization, i.e., pollen is passed down through the style and enters the ovule.

Step III.—A plant increases in size by cell-division and so does an ovule.

Give a diagram of an ovule, and show an ovule under the microscope.

Step IV.—Give a diagram of the cross-section of an ovule.

The embryo-sac is the most important part of the ovule; it afterwards contains the embryo of the future plant.

Step V.—Changes and growth go on within the embryo-sac until it is ready to be fertilized. Put diagrams of the successive stages of its growth on the board, and let O_____ draw the most important from memory.

Step VI.—Fertilization. When the embryo-sac reaches this stage the ovule is ready for fertilization. When the pollen-grain enters the ovary it passes into the ovule and into the embryo-sac. There it fuses with the oospore, which then changes into an oosphere. The oosphere becomes the embryo of the new plant. The secondary nucleus rapidly increases in size, laying up food material for the young plant, i.e., it becomes the cotyledon or cotyledons of the seed.

Step VII.—Recapitulation. Question O_____ on the structure of a pistil, and if there is time ask her to draw from memory certain of the diagrams, as these will test more exactly than questions if she has followed the whole process of growth.