Ontario Teachers' Manuals: Nature Study Part 8

How does each seed case open?

What are the seeds for?

How many seeds are in each case?

Why should a plant have so many seeds?

How are the seed cases fitted for protecting the seeds?

Are any two seeds alike in shape?

Are the seeds easy to find if they are spilled upon the ground?

What makes them hard to find?

Where do nearly all seeds spend the winter?

Of what use is the hard sh.e.l.l of the seed?

SEED DISPERSAL

Study only a few of the more striking examples of seed dispersal with the Form I cla.s.s. Seeds that fly and seeds that steal rides are good examples of cla.s.ses of seeds whose methods of dispersal will prove of interest to children.

LESSON ON SEEDS THAT FLY

~Materials.~--A milkweed pod; a ripe dandelion head.

~Introduction.~--A short conversation about the effects of the crowding of plants, as carrots and turnips, in a garden plot, and hence the need for the scattering of seeds.

~Observations.~--Open a milkweed pod in the presence of the cla.s.s, so that they may see how the pod opens, how beautifully the seeds are arranged, and how the silk tufts are so closely packed in together.

Allow a pupil to lift a seed out, blow it in the air, and observe how the silk opens out like an umbrella. Distribute seeds, one to each pupil. Ask the pupils to find out why this little airship is able to carry the seed. They will find that the seeds though broad, are thin and light, and the silky plumes very light.

Ask the pupils to release their milkweed seeds at recess, when out of school, and find out how far they can fly. This is an interesting experiment for a windy day.

The white b.a.l.l.s of the dandelion are next examined, the tiny seeds are found standing on tiptoe on a raised platform, each grasping a tiny parachute and waiting for a puff of wind to start them off. A pupil is permitted to give the puff. Seeds are distributed, and the means of flight is compared with that of the milkweed. The shape of the seeds is observed and also the tiny anchor points at the lower end of the seed for clutching the ground when the seed alights.

Another lesson on seeds that fly can be based on the study of tree seeds, using those of the maple, elm, ba.s.swood, pine, and spruce.

CORRELATIONS

1. Drawing of milkweed pods and seeds, and drawing of the dandelion seed-ball and the seeds when floating in the air.

2. Reading and literature. Interpret the thought and read expressively:

Dainty milkweed babies, wrapped in cradles green, Rocked by Mother Nature, fed by hands unseen, Brown coats have the darlings, slips of milky white, And wings, but that's a secret, they're folded out of sight.

TWIGS AND BUDS

The study of buds is a part of tree study and may be taken as observation work in the cla.s.s-room. This somewhat detailed study should follow the general lessons on tree study.

The materials for the lessons may be collected by the pupils at the time of the field lesson and kept fresh in a jar of water until required for use.

LESSON ON TWIGS

~Materials.~--A twig of horse-chestnut about six inches long, for each pupil.

A twig of the same tree with the leaves still on it.

~Observations.~--The twigs are distributed and the teacher asks the pupils to examine them and to describe all marks and projections that can be found on the twig.

Answers are required from the pupils separately. The pupil's answer in each case should be sufficiently clear for all the cla.s.s to recognize the feature that the answer is intended to describe. A few brief questions will guide the answerer in making his description more definite, but the description should be the result of the pupil's observation and expressed in his own words.

The meaning or use of each feature should be discussed, when possible, immediately after it has been described.

The following features will be discovered and the problems suggested will be solved:

The brown or greenish-brown bark.

The buds.

One bud (sometimes two) is at the end of the twig.

Some buds are along the side of the twig.

What caused the end bud to grow larger than the others?

There is a leaf scar under each bud.

Of what use is it to the bud to be between the twig and the leaf stalk?

The bands of rings, one or more on each twig.

The tiny oval pores, each surrounded by a little raised band.

The detailed study of the buds is left for a separate lesson.

FURTHER STUDY OF TWIGS

The study in detail of various features is ill.u.s.trated in the following:

Look closely at the leaf scars and describe them fully, as to shape, colour, and marks.

Do the scars look like fresh wounds, or are they healed over? Of what use to the tree is the healing of the scar?

We will learn later that the part of the twig between each pair of bands of rings represents one year's growth. How old is your twig? Who has the oldest twig?

Do all twigs grow at the same rate?