(f) What the river carries in its water.
(g) What plants and animals may be seen there.
3. To a circus to see the wild animals, so as to be better able to realize what the animals that lived when the Tree-dwellers did were like.
4. To a farm to find—
(a) What animals live there, how they are taken care of, and how they differ from wild animals.
(b) What plants are cultivated on the farm and in the gardens, how they are cultivated, and how they differ from the wild plants that can be found in uncultivated spots.
5. To a gravel bed or stone quarry to find—
(a) What kinds of stone are there.
(b) How stone is quarried and what it is used for.
(c) A problem with reference to how the gravel bed or the stone quarry was made.