The range of ability possessed by children of the same grade in the subjects commonly taught seems not always to be clear in the minds of teachers.  It will be discussed at greater length in another chapter, but it is important for the consideration of individual differences to present some data at this time.  If we rate the quality of work done in English composition from 10 to 100 per cent, being careful to evaluate as accurately as possible the merit of the composition written, we will find for a seventh and an eighth grade a condition indicated by the following table: 

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QUALITY OF COMPOSITION GRADES
7 8
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No. of Pupils
Rated at 10 2 1
Rated at 20 6 6
Rated at 30 8 8
Rated at 40 7 8
Rated at 50 2 4
Rated at 60 1 1
Rated at 70 1 1
Rated at 80 1 1
Rated at 90 1 1
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The table reads as follows:  two pupils in the seventh grade and one in the eighth wrote compositions rated at 10; six seventh-grade and six eighth-grade pupils wrote compositions rated at 20, and so on for the whole table.

A similar condition of affairs is indicated if we ask how many of a given type of addition problems are solved correctly in eight minutes by a fifth- and a sixth-grade class.

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NUMBER OF GRADES
PROBLEMS 5 6
---------------------------------------------
No. of Pupils
0 2 3
1 6 6
2 6 6
3 6 6
4 4 5
5 4 5
6 3 4
7 1 2
8 1 1
9 1 1
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In like manner, if we measure the quality of work done in penmanship for a fifth and sixth grade, with a system of scoring that ranks the penmanship in equal steps from a quality which, is ranked four up to a quality which is ranked eighteen, we find the following results: 

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QUALITY OF PENMANSHIP GRADES
5 6
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No. of Pupils
Rated at 4 5 6
Rated at 5 1 1
Rated at 6 0 0
Rated at 7 2 4
Rated at 8 10 4
Rated at 9 12 1