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In the second column the number (N) of study participants is reported for each grade and overall; the third column reports a descriptive statistics (mean and standard deviation (SD)) of the study participants’ age for each grade and overall.
| Study participants | N | Mean age in years (± SD) |
|---|---|---|
| 2nd grade | 20 | 7.5 (± 0.2) |
| 3rd grade | 31 | 8.4 (± 0.2) |
| 4th grade | 22 | 9.6 (± 0.2) |
| 5th grade | 21 | 10.5 (± 0.3) |
| Total | 94 | 9.0 (± 1.3) |
