CHAPTER VIII

FORM II

SPRING

GARDEN WORK

The pupils have now arrived at an age when they are able to do most of

the work of preparing and planting their own plots. The seeds have been

selected and placed in readiness for planting long before the ground is

ready. The plans for the garden and the varieties to be sown in the

different plots have likewise been arranged. Fertilizers, lines, tools,

and labels are made ready for use. With such thorough preparation the

making and planting of the garden becomes a pleasure and a delight to

both teacher and pupils. The garden diary should begin as soon as the

snow disappears from the garden and be continued until all the work is

completed in the autumn, and the garden again blanketed in snow.

The main points to be safeguarded are:

1. Thorough cultivation and fertilization.

2. The best available seed carefully planted. Guard against thick sowing

and deep covering.

3. Frequent cultivation and careful thinning while the plants are quite

small.

4. Vigilance in detecting the appearance of cutworms or other injurious

insects and promptness in combating them.

5. Protection of the garden against injury from dogs, pigs, poultry, and

English sparrows.

6. Failure of some plots, through the owner's absence from school for

long periods.

COMBATING GARDEN PESTS

CUTWORMS

In gardens where the soil is light or sandy, cutworms are most likely to

be troublesome. Watch for them about the time that the plants are nicely

above ground. They come up at night and cut the young plants off just

above the ground. They are about an inch long, gray and brown, fat and

greasy-looking. To protect the plants put one quarter of a pound of

paris-green with twenty-five pounds of slightly moistened bran, using a

little sugar in the water and stirring the paris-green into the bran

very thoroughly. If too wet, add more dry bran. It should crumble

through the fingers. Sprinkle a little of this mixture with the fingers

along the row close to the plants. The cutworms eat this poisoned bran

quite readily. Care must be exercised in using this poison lest poultry

should get at it. On the other hand, poultry should not be allowed to

get into the garden. Wrapping a piece of paper around the stem when

transplanting young plants will help to save them from cutworms.

ROOT MAGGOTS

Root maggots of cabbage, radish, and onions are the larvae of flies

similar in appearance to house-flies but a little smaller. When the

plants are young, the flies lay their white eggs on the stem close to

the ground. When the eggs hatch, the larvae crawl down under the ground

and cause the plants to decay. The wilting of the leaves is the first

sign of the trouble. Prevention is better than cure in this case. Dust

some dry white hellebore along the rows of onions or radishes and around

the cabbage plants; or, for radishes, make a decoction of insect powder

(Pyrethrum), four ounces to one gallon of water, and pour around the

root, using half a teacupful to each plant.

FLEA-BEETLES

The turnip flea-beetle quickly destroys young plants of the cruciferae

family by eating their leaves. Paris-green, one part to twenty parts of

pulverized gypsum (land plaster) dusted on the plants while damp, helps

to destroy these insects.

_To the teacher._--When pupils who are absent find it impossible to give

the necessary attention to their garden plots at school, they should

turn them over to other pupils or to the teacher, who may at his own

discretion use the produce for purposes of general garden revenue.

SEED GERMINATION

The seeds for the garden should be purchased quite early in the spring.

As the planting of poor seed is often the cause of much disappointment,

it is well to test the germinating power of the different varieties to

be planted. The pupils of this Form should test especially those

varieties which they have chosen. To do this, place about twenty-five

seeds in a germinating dish, which may be made as follows: Take a deep

plate, such as a soup plate, fill it about half full of moist sand, and

spread over this a piece of moist cloth. Put the seeds upon this cloth

and cover them with a second piece of damp cloth or moss. To prevent

drying out invert over it another plate and set all in a warm dry place

(about 70 to 80 degrees F.). After a few days count the number of seeds

that have germinated. This will be a guide in planting as to how thick

the seed should be sown.

The pupils should watch the development of germinating grains, such as

corn and beans, germinated in the same way as in the last exercise. The

following points may be observed:

1. The first change noticed. (Swelling of the seed)

2. The appearance of a growing shoot and its direction. (Root)

3. The second shoot and its direction. (Stem)

4. The appearance of the first pair of leaves.

5. The appearance of root-hairs and rootlets.

6. What becomes of the main body of the seed.

7. How the second pair of leaves differs from the first pair.

8. Length of time required to produce the first pair of leaves.

Pupils may be taught the conditions that are necessary for the

germination of seeds by means of a few simple experiments which can be

carried on in the school-room.

1. In February, plant a few seeds of the pea, or oat, or wheat, in a box

of soil, and place the box outside the school window.

2. In April, plant a few seeds similar to those used in No. 1, in a box

of perfectly dry soil, and set the box inside the school window.

3. Plant a few seeds similar to those used in No. 1, in a jar containing

soil that is kept very wet, and set the jar in the school window.

4. Plant a few seeds, similar to those used in No. 1. in a box

containing soil that is moist but not wet, and set the box in the school

window.

5. Plant seeds as in No. 4, except that the box is kept in a dark

cupboard.

Compare the results of the above with reference to:

1. The number of seeds that germinate.

2. The growth and condition of the plants.

Form conclusions with reference to:

1. The conditions that are required for seed germination.

2. The benefits of well-drained soil.

Pupils make drawings showing the boxes and plants.

PLANTS FOR INDIVIDUAL PLOTS

The pupils of this Form should not attempt to grow more than two

varieties of flowers and two of vegetables. Of flowers, mixed asters and

Shirley poppy are to be recommended, the poppy being an early blooming

flower and the aster late blooming. Carrots and radishes are desirable

vegetables, as the carrot matures late and the radish early. Two or

three crops of radishes may be grown on the same ground in one season.

Besides these, a few others should be chosen for special study, such as

the potato, onion, corn, and sunflower.

STUDIES BASED ON OBSERVATIONS OF GROWING PLANTS

Attention should be given to the growing habits of plants, the size and

rate of development, the method of multiplying and propagation, and the

part used for food. The potato is a tuber which is nothing more than

the swollen end of an underground stem; the onion a bulb composed of the

bases of thickened leaves; the corn an example of a jointed stem or

grass having two kinds of flowers, the tassels being the staminate

flowers and the cob with its silk the pistillate ones; the sunflower an

example of a compound flower made up of many little flowers each of

which produces a single seed.

Observations should also be made upon the progress in germination of the

nuts and other tree seeds collected in the fall. When the seeds fall

from the elms and soft maples in the spring, some of them should be

collected and planted in the forestry plot, or nursery.

PLANTING AND CARE OF SWEET-PEAS

1. Sow as early as possible in spring.

2. Sow on well-drained land and never in the shade or near grass. Grass

roots rob the sweet-pea roots of water.

3. Use a small amount of fertilizer--well-rotted manure spaded deeply

into the soil. This is best done in the autumn.

4. Make the trench in the fall about five or six inches deep.

5. Plant in a trench in April from half an inch to an inch apart.

6. Cover from three inches to four inches deep.

7. Water thoroughly once or twice a week, and have the soil lower along

the row than farther out, so as to hold the water.

8. Put a mulch of lawn clippings along the row on each side to prevent

drying out.

WILD FLOWERS

Arrange an excursion to the woods when the spring flowers are in bloom.

Keep a flower calendar, showing:

1. The date when a plant was first found in bloom

2. The name of the plant

3. Place where found

4. Name of the pupil who found it.

When in the woods discuss the following points:

1. Why these wild flowers come into bloom so early in spring. They have

a large supply of food stored up from the previous summer.

2. Dig down with a trowel or heavy knife and find this storehouse of

food. It may be in the form of bulb, corm, or rhizome.

3. The blooming of the spring flowers in the woods before the leaves of

the trees reach their full development, thus taking advantage of the

sunlight.

4. Mark a few clumps or individual plants and visit them again after a

month. Look for the growing fruit with its seeds.

5. The leaves of the hepatica seen at the time when the blossoms appear

are leaves which grew the previous season. Dig up a plant and notice the

new leaves starting.

6. The kind of soil each seems to grow best in and the amount of light

it receives.

7. Have the pupils examine the flowers and leave them growing. They

should gather a few for the school-room.

8. Have the pupils write a short account of their visit to the woods.

Have them make drawings of the different flowers collected.

Dig up a few specimens of wild flowers and transplant in a shady corner

in the grounds or school garden. The following varieties are suggested

for special observation and study: hepatica, violet, anemone, columbine,

Indian turnip, marsh marigold.

Teach one or two lessons on wild flowers, similar to the lessons

illustrated for the nasturtium.

WEEDS

Pupils in this Form should learn to identify most of the weeds that are

found in the garden plots and a few of those commonly found in fields

and along roadsides. The large bulletin _Farm Weeds_, published by the

Dominion Department of Agriculture, will be of great value in helping to

identify the weeds and also in gaining useful information regarding them

and the best means of eradicating them.

The following species are recommended for special study during the

season: mustard (such varieties as are found in the vicinity), Canada

thistle, purslane, lamb's quarter, pink-rooted pigweed, and quack grass.

The pupils should be familiar with the general appearance of the plant;

its appearance when coming up in the spring; whether annual, biennial,

or perennial; nature of the root, and whether hard to pull up; if hard

to eradicate, why so; its rate of growth compared with the garden

plants; the number of seeds produced by a single plant; how the seeds

are scattered.

THE APPLE TREE

(When the buds are beginning to open)

FIELD EXERCISE

The pupils, during an excursion that is conducted by the teacher or

while making individual observations, obtain answers to problems of the

following type:

What is the shape of the top of the apple tree?

Are all apple trees of the same shape?

What is the height of the trunk?

Measure the girth of the trunk of the largest?

Are the leaf buds and flower buds more numerous near the inside of the

tree top or more numerous at the outer part of the top?

_To the teacher._--When discussing the answers to the above problems,

develop the conception of the convenience of the low stature of the tree

for gathering the apples, of the wide-spreading branches for bearing a

large crop, of the stoutness of the trunk for supporting the weight, and

also of the position of the buds as adapting them for securing sunshine.

CLASS-ROOM LESSON ON THE APPLE TREE

~Materials.~--Twigs bearing flower and leaf buds. These are gathered by

the pupils from the apple trees that were studied during the field

exercises.

Each pupil finds on his twig the objects and markings, etc., as in the

following outline:

Describe the shape of the twig.

Where were the apples that grew last year attached?

Describe the positions of the buds on the twigs.

Which buds are the larger, those at the end or those on the side of the

twig?

Describe the condition of the bud scales.

Open the buds and find what they contain.

Of what use are the bud scales?

How many blossoms are in one bud?

Of what use to the young leaves is the downy covering?

FIELD EXERCISE FOLLOWING CLASS-ROOM LESSON

(Just after the blossoms are fully open)

What is the colour of the apple blossom?

Find the little green cup on which the petals rest.

Describe the cup.

Find the other things that are on the rim of, or that are within, the

cup. What are they?

What insects visit the flowers?

Does the cup fall off when the petals fall?

Does the cup close up as soon as the petals fall?

What does the green cup grow to be?

_To the teacher._--Apple trees have somewhat round or pyramid-shaped

tops, varying in detail with the variety of apple tree. The twigs are

short and usually crooked. The fruit twigs are called spurs. The buds at

the ends of the twigs and spurs are the largest and contain both leaves

and blossoms, and there are usually several blossoms in each bud. The

bud scales burst apart and drop off as the leaves and blossoms develop.

The side buds produce leaves only. The petals and pollen boxes are borne

on the rim of the green cup, and inside the cup are found the five tips

of the seed cases. When the petals drop off, the rim of the cup remains

spread out for a short time. This is the proper time for spraying, so

that the cup may hold a drop of poison to kill the tiny worms which

cause apples to be wormy. It is the green cup that grows and forms the

flesh of the apple.

Orchard trees suitable for lessons for Form II are apple, plum, pear,

peach, and cherry.

BIRD STUDY

A valuable exercise in bird study, suitable for the pupils of Form II,

is the study of a pair of birds and the history of their home through

the entire season.

A record, with dates, should be kept, and the following topics are

suggested for observation:

Where the nest is located, protection of the nest, part of building done

by each bird; eggs, number, colour, size, time required for hatching;

young birds, number, description, how fed and upon what foods, time

required before ready to leave the nest; history for a time after

leaving the nest.

Birds suitable for study by the pupils of Form II are the crow, flicker,

downy woodpecker, blue-bird, chipping-sparrow, phoebe, wren.

Correlate with art, by requiring drawings and models of the nest and its

surroundings, and with language, by having pupils write the history of

the nest and family.

THE TOAD

FIELD EXERCISES

Direct the pupils to watch for toads under the street lamps and on the

lawns in the evenings, and to observe what they are doing.

Find out, by turning over boards, logs of wood, stones, and old stumps,

where toads spend the daytime.

If there is a sandy beach near by, an interesting nature lesson is to

trace a toad to its daytime retreat under a log or stone. Its wanderings

and adventures during the night can be traced from the record that its

trail makes in the sand.

Are toads that live in light-coloured sand of the same colour as those

that live in black clay? Of what value to the toad are these differences

in colour?

The pupils are thus led to see that although the toad is not a handsome

animal, yet its rough, dark skin is of great value to it for concealment

among the lumps of soil with which it harmonizes.

Can a dog be induced to seize a toad? Will he seize it as readily a

second time as he did the first? The secretion from the glands of the

toad have a biting, acid effect on the dog's mouth. This secretion will

not injure a person's hands unless the skin is broken, and even then it

does not "cause warts".

How many toads can you find on your lawn in one evening? How many in the

vegetable garden? How many in the flower beds?

Place a toad on loose soil among some weeds and observe how it proceeds

to get out of sight.

Is it true that a toad is attracted by music? Give reasons for your

answer.

CLASS-ROOM LESSON

Secure a few living toads and keep them in a box covered with a pane of

glass. Be sure to put moist soil and damp moss in the bottom of the box

in which toads, frogs, newts, or snakes are kept. This enables these

animals to live in comfort, and they soon become sufficiently accustomed

to their surroundings to act in a normal way.

~Observation.~--By flicking in front of a toad a small feather or a bit of

meat attached to a thread, the darting out of the tongue for catching

prey on its adhesive surface may be observed.

The children, by bringing slugs, caterpillars, grubs, and various

insects for the toads, may learn what composes the food of the animal.

It is to be observed that the toad does not snap at an object until it

moves.

DETAILED STUDY

~Observation.~--General shape; division into head, trunk, and limbs; size

of head and mouth; position and structure of eyes and ears; difference

in the size of the fore and hind limbs, and explanation of this

difference by references to the use of the limbs; the hind foot, uses of

the web; the glands on the surface of the body and their uses for

protection.

Why is a large mouth useful? How are the ears fitted for life in water?

In conclusion, the teacher should make sure that the pupils appreciate

the usefulness of the toad and also the beauty represented in its

adaptations to its conditions of life. In these particulars the toad is

a good illustration of the adage "Handsome is that handsome does".

LIFE HISTORY OF THE TOAD

In early spring look for the toads on the surface of the water in ponds.

The music of the toads at this time of year has been described by one

naturalist as "one of the sweetest sounds of nature".

The eggs may be found in these ponds at this time. They are attached to

long strings of jelly which entwine among grasses and other objects in

the ponds. (Frogs' eggs are in masses of jelly, not in strings.) Place

some of the eggs in a jar of water and set the jar in the window of the

school-room. A great mass of eggs is too much to put in a jar, a few

dozen eggs in a pint of water will be more likely to develop. The water

in the jar should be changed twice a week.

~Observations.~--The light and dark areas of the eggs, the dark area

gradually increasing in size; the increase in the length of the egg; the

gradual change of the dark area into the general shape of a tadpole with

head and tail, the first appearance of the gills, the separation from

the jelly, the movement by means of the tail, the disappearance of the

gills, the growth of the hind legs and, later, of the forelegs, and the

disappearance of the tail.

~Questions and Observations.~--What is the use of the dark colour of the

area from which the tadpole is formed?

Explain the uses of the strings of jelly.

Describe how the tadpole swims.

Upon what does the young tadpole feed?

What is the advantage of external gills at this stage in the tadpole's

life?

~Later Observations.~--The disappearance of the gills, the budding out of

the hind legs and, later, the forelegs. While the legs are growing out,

the tail gradually becomes smaller, at the same time the shape changes

to that of the adult toad with a broad body and large mouth and eyes.

~Questions.~--What movements has the toad which the tadpole did not have?

What makes these movements possible?

Why is the mouth of the toad better suited to its manner of life than

the small mouth of the tadpole would be?

Of what advantage to the tadpole was the smooth outline of its body, and

why is the rougher outline of the toad's body better suited for the life

of the latter?

Why would gills be unsuitable for the life of the toad?

_To the teacher._--From the dark area of the egg the tadpole develops,

the dark colour absorbs the sunlight, and this causes growth. The jelly

holds the eggs up so that the sun can reach them and it also keeps them

from being swept away by the water. The tadpole is very small, and

external gills are needed to keep it in very close contact with the

water. The tail does not drop off, the substance in it is absorbed into

the body of the growing toad to serve as nutriment.

Since all the changes in the development of the toad from egg to adult

form take place in about one month, this comparatively rapid development

makes the life history of the toad particularly suitable for observation

work.

The development of the eggs of the frog or newt may be studied from

preparations made in precisely the same way as those for the study of

the development of the toad.

If observations on the developments of two forms are carried on at one

time, interesting comparisons can be made on such points as, shape and

size of the eggs, time required for development, shapes and colours of

the tadpoles, activity of the tadpoles, etc.

THE EARTHWORM

~Time.~--May or June, in connection with gardening, when the working of

the worms in the moist soil of the garden is quite noticeable.

Outdoor studies may be assigned, as:

Observe the loose soil at the entrance to the burrows. Insert a straw in

the burrow and, following it, dig downward with a garden trowel and

learn the nature of the earthworm's home.

Are earthworms ever found out of their burrows during the day? If so, on

what kind of days? Why do earthworms burrow deep in dry weather?

Earthworms can breathe only when the surfaces of their bodies are in

moist conditions.

Go out at night with a lantern to where earthworms are known to have

burrows, observe the worms stretched out with the rear ends of their

bodies attached to the burrows, and note how quickly they draw back when

they are touched. Do they draw back if the ground is jarred near them?

Do they draw back when the light falls upon them?

State the facts which are taught by the observations which were made on

the above topics.

CLASS-ROOM LESSON

Put two or three earthworms into a jar of rich, damp soil, on top of

which there is a layer of sand a quarter of an inch thick. Put bits of

cabbage, onion, grass, and other plants on the surface and cover the jar

with a glass slip or cardboard.

After a few days, examine the jar, noting the number of burrows, the

foods selected, the castings, the food dragged into the burrows. Pour

water into the jar and observe the actions of the worms. Can an

earthworm live in water?

Place an earthworm on a moist plate or board and direct the pupils to

study it, as follows:

Distinguish the head from the rear end, the upper from the lower

surface. Observe the means of living. To assist in the latter

observation, stroke the worm from rear to head and find the four double

rows of bristles. Why is it difficult to pull an earthworm out of its

burrow?

Find the mouth. Has the earthworm any eyes, ears, or nose? Place a pin

in the path of a moving worm and try to explain why it turns aside

before touching the obstacle. Test the sensitiveness to feeling. Why is

it cruel to put an earthworm on a fishhook?

From the soil castings found in the jar, infer the value of earthworms

for enriching and pulverizing soil. (See "Soil Studies", p. 269.)

REFERENCES

Bailey and Coleman: _First Course in Biology._ Macmillan Co. $1.25.

Crawford: _Guide to Nature Study._ The Copp, Clark Co. 90 cents.

Kellogg: _Elementary Zoology._ Holt & Co. $1.35.

THE AQUARIUM

A large glass aquarium may be purchased from any School Supply Company

at a cost of a few dollars, but a small globe-shaped aquarium such as is

used for gold-fishes will be found suitable for school purposes. If it

is not possible to secure either of these, a large glass jar, such as a

battery jar or large fruit jar, will be found to answer quite well.

To set up the aquarium, put into the jar about two inches of clean shore

sand (sand from a sand pit, washed until the water comes away clear,

will do). Secure from a pond some water-plants, place these in the jar

with their roots covered with sand and secured in position by small

stones. Pour in water until the jar is nearly full, taking care not to

wash the roots out of place, and then put in a freshwater clam and a few

water snails. These are scavengers, for the clam feeds upon organisms

that float in the water, while the snails eat the green scum that grows

on the glass.

The other aquarium specimens may now be put in. One fish about three

inches long to a gallon of water is about the right proportion. When

there is a sufficient quantity of plant life to keep the water properly

oxygenated and enough animal life to supply the carbon dioxide necessary

to keep the plants growing well, the aquarium is said to be _balanced_.

The balanced aquarium does not require that the water be changed more

often than once in two months.

Too much direct sunlight causes too rapid growth of green slime, hence

the aquarium should not be set in a window. Close to a window through

which the sun shines upon it for an hour or longer each day is the best

position.

Do not supply more food to the animals in the aquarium than they can eat

up clean.

Crayfish, perch, trout, and other freshwater fishes are destructive of

insect larvae and other aquarium specimens, hence care must be taken in

selecting the specimens that are put together into an aquarium.

Suitable animals for the aquarium: mosquito larvae, dragon-fly larvae,

caddice-fly larvae, crayfish, clam, water snails, tadpoles, fish, frog,

turtle.

AQUARIUM SPECIMENS

MOSQUITO

Time.--May or June.

~Questions and Observations.~--At what time of the year are mosquitoes

most plentiful? In what localities are they most plentiful? Why are

they most plentiful in these places? Are mosquitoes ever seen during

fall or winter? How do you account for their rapid increase in number

early in summer?

How do mosquitoes find their victims? Observe the humming noise and try

to discover how it is made.

Watch a mosquito as it draws blood from your hand. Does the point of the

beak pierce the skin?

Capture a number of mosquitoes and place them in a jar containing some

water and a few straws or sticks standing upright out of the water.

Cover the mouth of the jar with a glass plate or fine gauze. Watch for

the rafts of mosquitoes' eggs on the surface of the water.

The eggs may also be found on the surface of ponds or open rain barrels,

and may be transferred to water in a jar in the laboratory.

STUDY OF THE ADULT FORM

Note the shape, colour, sucking tube, wings, and legs. Compare with the

house-fly.

Distinguish the male insect from the female; the former has feathery

feelers, and has mouth parts unsuited for biting.

How many kinds of mosquitoes have you seen? Direct attention to the kind

which causes the spread of malaria. It is recognized by its habit of

standing with its body pointing at right angles to the surface on which

its feet are placed or, in other words, it appears to stand on its head.

THE DEVELOPMENT

Describe the egg raft.

Observe the wigglers (hatched in about a day); the divisions of the

body of the wigglers; position of the wigglers when at rest. Observe

that the tail end is upward. Lead the pupils to perceive that this is

the means of getting air.

Observe the rapid movement toward the bottom when disturbed; the means

of causing this movement; the change into the large-headed pupae--a

change which takes place about ten days after hatching; the almost

motionless character of the pupae; the change from the pupae forms into

the adult--a change which takes place at about the fourth day of pupae

life.

Put some mosquito larvae (wigglers) into the fish aquarium. Are

mosquitoes of any use? The wigglers are the food on which some young

fishes live. Young bass and trout feed upon them.

Put some kerosene on the surface of a jar in which there are mosquito

larvae. Describe a method of destroying mosquitoes.

The teacher tells about the mosquito as the cause of the spread of

malaria. From the fact that the eggs hatch on stagnant water, deduce a

benefit arising from the draining of land.

REFERENCES

Silcox and Stevenson: _Modern Nature Study_

Hodge: _Nature Study and Life_

CADDICE-FLY

Time: May.

The caddice-flies are very interesting insects, owing to the habits of

the larvae of building little cases of wood, stones, or shells, in which

they pass their development stages under water.

These larvae are easily found during the month of May in little streams

of water everywhere throughout the Province. Look for what at first

sight appears to be a bit of twig or a cylinder of stone about an inch

long moving along the bottom as though carried by currents. Closer

observation will result in the discovery that this is a little case

composed of grains, of bits of stick, or of sand and tiny shells, and

the head of the occupant may be seen projecting from one end.

Collect some of these larvae in a jar of water and transfer them to the

aquarium. Direct the pupils to look for others in the streams, so that

they may observe their appearances and movements in their natural

environment. If kept in jars, the water must be changed every day, and

the top should be covered to prevent the escape of the adults.

~Observe.~--The shape of the various kinds of cases; the materials, and

how fastened together (chiefly by silk); the part of the larva that

protrudes from the case; the movement, and how caused; the fitness of

the case as a protection. Note hardness, colour, and shape as protective

features.

The pupils will be fortunate if they observe the sudden rise of the

larva to the surface of the water and the almost instantaneous change

into the four-winged fly.

INSECTS SUITABLE FOR LESSONS IN FORM II

Walking-stick insect, katydid, cricket, mole-cricket, clothes-moth,

giant water-bug, potato beetle, click-beetle, luna moth, and

swallow-tail butterfly.

Ontario Teachers' Manuals: Nature Study · 第 8 / 14 章