n dioxide and oxygen in the water.

_B._ Make a list of words in your lessons in other subjects for to-day
that you need to look up in order to understand the lessons. This should
be done daily, whether assigned or not.

34. +Choice of Words Adapted to the Reader.+--Words familiar to the reader
should be used. Since the reader's ability to understand the thought of a
paragraph depends to some extent upon his understanding of the words
employed, it is necessary for the writer to choose words that will be
understood by those whom he addresses. Of course we cannot tell whether a
particular word will be understood by our readers, but, in case there is
doubt, it is well to substitute one that is more likely to be understood.
When you have written anything, it is well to ask yourself the question,
Have I used words with which _the reader_ is probably familiar?

+Theme XV.+---_Write a theme about one of the following subjects, using
words that you think will be understood by your readers:_--

1. How we breathe.
2. How to make a kite.
3. The causes of the seasons.
4. Why wood floats on water.
5. The use of baking powder.
6. The difference between arithmetic and algebra.

(Have you said what you meant to say? Have you used words that your reader
will understand? Find your longest sentence. Is its meaning clear? Notice
the short sentences. Should some of them be united into a longer one?)

+35. Word Selection.+--There are many shades of meaning which differ but
little, and a careful writer will select just the word that best conveys
his thought. The reader needs to be no less careful in determining the
exact meaning that the writer intends to convey. Exercises in synonyms are
thus of double importance (Section 21).

Another source of error, both in acquiring and expressing thought, arises
from the confusion of similar words. Some similarity of spelling causes
one word to be substituted for another. There are many words and
expressions that are so often interchanged that some time may be spent
with profit upon exercises in determining their correct usage. These
usually consist of brief reports to the class that set forth the meanings
of the words, show their uses, and illustrate their differences.

In preparing such reports, determine the meaning of the words from as many
sources as are available. The usual meaning can be determined from the
dictionary. A fuller treatment is given in some dictionaries in