1
MINISTRY OF EDUCATION AND TRAINING
HANOI NATIONAL UNIVERSITY OF EDUCATION
======================
NGUYEN THI BICH NGOC

RESEARCH ON SOME BIOLOGICAL CRITERIA AND
INTELLECTUAL CAPACITY OF THE 11 - 17 YEAR - OLD
MOUNTAINOUS PUPILS IN VINH PHUC AND PHU THO PROVINCES Major : Physiology of humans and animals
Code : 62.42.30.01
SUMMARY OF PH.D DISSERTATION
HA NOI, 2013
This study is completed at Faculty of Biology,
Hanoi National University of Education


2. Nguyen Thi Bich Ngoc & Ta Thuy Lan (2010), The sensation-motor
flexex time of the Kinh and Sandiu pupils from 11 tob17 years old in Vinh
Phuc province, Journal of Physiology Vietnam, The Physiology Vietnam,
The Vietnam Medical Association, Vol.14 No 4.p.56-60.
3. Ta Thuy Lan & Nguyen Thi Bich Ngoc (2011), The ability of attention and
short-term memory of the Kinh and Sandiu pupils from 11 to15 years old in
Vinh Phuc province, Journal of Physiology Vietnam, The Physiology Vietnam,
The Vietnam Medical Association Vol.15 No 2, p. 30-35.
4. Ta Thuy Lan, Nguyen Thi Bich Ngoc (2012), Research on the feeling
reflective time - movement of Muong ethnic minority pupils aged 11 to 17 in Phu
Tho province, Reports on Research and Teaching in Vietnam Biology, National
Scientific Conference First, Ministry of Education and Training, Hanoi National
University of Education, The Agricultural Publisher, p.191-196.
5. Nguyen Thi Bich Ngoc, Ta Thuy Lan (2012), Research on the
intellectual capacity of Kinh and San Diu pupils from 11 to 17 years old in
Vinh Phuc and Phu Tho provinces, Report on Research and Teaching
Biology in Vietnam, Proceedings of the 1
ST
National Scientific Conference
on Biological Research and Teaching in Vietnam, Ministry of Education
and Training, Hanoi National University of Education, The Agricultural
Publisher, p.134-139.

4
INTRODUCTION
1. REASONS FOR CHOOSING TOPICS
Research on human biology is a fundamental and large area, requiring the
participation of many scientists from different fields such as medicine, biology,
cybernetics, chemistry and mathematics. During the innovative process of our
country, many studies on biological indicators and wisdom of Vietnamese


5
children characteristic development of school age children in order to
improve quality of care, protection and education for these children.
4. STRUCTURE OF THE THESIS
In addition to the introduction, conclusion and recommendations, the
main content of this thesis consists of 4 chapters: Chapter 1: Overview of
the research; Chapter 2: Subjects and Research Methods; Chapter 3:
Findings; Chapter 4: Discussion.
Chapter 1
OVERVIEW OF THE RESEARCH
1.1. OVERVIEW OF CHILDREN'S DEVELOPMENT STAGE
The process of physical growth and development of a child has
uneven periods; there are periods of rapid growth interspersing with slow
growth periods, in which each stage has different morphological anatomy
and physiology characteristics.
1.2. RESEARCH ON BIOLOGICAL INDICATORS AND INTELLECTUAL
CAPACITY IN THE WORLD
The researches such as PhD theses of Christian Friedrich Jampert,
Philibert Guerneau de Montbeilard, D 'Arcy Thomson, Martin R, Cotes J.E.
(1966), Camphell E.J.M (1968), Ivan Sechenov, Pavlov I.P, Terman L,
Wechsler D, Ukhtomski A.A, Vygotski L.X Under the impact of living
conditions and genetic characteristics, the development in terms of a child’
body in terms morphology, function and intelligence completes with ages.
1.3. RESEARCH ON BIOLOGICAL INDICATORS AND
INTELLECTUAL CAPACITY IN VIETNAM
Studies prior to 1975 are collected in "Biological constant of Vietnamese
people”, which summarized adequately in terms of biological indicators of
Vietnamese people. After the unification (1975), many authors have studied this
topic such as Ta Thuy Lan, Tran Thi Loan, Do Cong Huynh, Tham Thi Hoang

methods of Do Cong Huynh and colleges.
- Research method of puberty is used the retrospective interview
methods.
- Research method of wisdom is used the Raven's test method.
- Memory is determined by Nechaiev's method.
- Ability to pay attention is determined by Ochan Bourdon's method.
- The survey data were processed using SPSS 16.0 software and Excel
on computer with statistical methods used in biology.
Chapter 3
FINDINGS
3.1. PUBERTY PERIOD
3.1.1. Puperty of female pupils
3.1.1.1. Percentage of pubertal female pupils
Results show that, at the age of 11 years old, there are some female
pupils being pubertal. Most female pupils in three ethnic groups become

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pubertal at the age of 12 to 14. All female pupils are pubertal at the age of
15. Puberty period of Kinh female pupils is earlier than those of Muong and
San Diu female pupils.
3.1.1.2. Puberty age of female pupils
Results show that, puberty age of Kinh female pupils is 12 years and
10 months ± 1 year and 3 months, these of Muong female pupils is 13 years
2 months ± 1 year 3 months and that of San Diu female pupils in 13 years 4
months ± 1 year 8 months.
The age having the first menstrual flux of Kinh pupils is earlier than that
of Muong and San Diu pupils with p<0.05, while there are no differences in age
having the first menstrual flux among Muong and San Diu pupils.
3.1.2. Puperty of male pupils
3.1.2.1. Percentage of pubertal male pupils

Height (cm)

21
- XXp(1-2)
Male (1)
Female (2)
n
X
± SD
Increase
n
X
± SD
Increase
Kinh
11
120
134.85  5.09
-
121
136.68 4.41
-
-1.83
<0.05

6.36
119
153.08 4.61
2.15
3.81
<0.05
16
117
161.67 3.29
4.78
120
155.89 4.33
2.81
5.78
<0.05
17
118
164.45 3.98
2.78
120
156.25 3.55
0.36
8.20
<0.05
Average increase/ year
4.93

3.26

Muong

148.56 3.55
6.72
84
149.96 3.52
4.93
-1.40
<0.05
15
81
155.25 4.46
6.69
85
152.25 4.38
2.29
3.00
<0.05
16
83
159.23 4.71
3.98
86
155.19 5.37
2.94
4.04
<0.05
17
85
162.85 5.24
3.62
83

59
141.07 5.62
4.76
60
144.57 5.73
6.62
-3.50
<0.05
14
61
144.85 4.94
3.78
57
149.29 5.54
4.72
-4.44
<0.05
15
62
151.67 4.25
6.82
60
151.86 4.97
2.57
0.19
>0.05
16
60
155.96 4.88
4.29

the same. In the period of 11 to 13 years old, weight of male and female
pupils is similar. Weight of female pupils larger than male pupils at the time
of 14 to 15 years old, weight of male pupils is greater than that of female
pupils in the period of 16 to 17 years old (p<0.05). Particularly, Muong
pupils at the age of 14 to 15, the weight difference between male and female
pupils is negligible. This leads to a cross-section of weight growth in Table

9
3.2 at 15 to 16 years old for pupils in all three ethnic Kinh, Muong and San
Diu. Comparing the weight of pupils in three ethnic groups showed that the
weight of Kinh pupils is larger than Muong and San Diu pupils with p<0.05.
Table 3.6. Weight of the pupils by age, ethnic group and gender
Ethnic
group
Age
Weight (kg)

21
- XXp(1-2)
Male (1)
Female (2)
n
X
± SD
Increase
n
X

3.07
-0.96
>0.05
14
122
38.81  4.96
4.23
120
40.46  4.95
4.92
-1.65
<0.05
15
121
42.57  4.58
3.76
119
44.49  4.64
4.03
-1.92
<0.05
16
117
46.85  4.37
4.28
120
45.76  4.34
1.27
1.09
>0.05

84
31.06  3.86
1.70
0.89
>0.05
13
82
34.45  3.09
2.50
86
33.87  3.35
2.81
0.58
>0.05
14
84
37.96  4.34
3.51
84
37.81  3.07
3.94
0.15
>0.05
15
81
42.15  3.27
4.19
85
42.25  4.53
4.44

-
61
28.85  4.07
-
0.78
>0.05
12
62
32.01  3.49
2.38
58
31.24  3.58
2.39
0.77
>0.05
13
59
34.66  4.47
2.65
60
34.09  3.29
2.85
0.57
>0.05
14
61
36.95  4.75
2.29
57
39.12  3.96

Average increase/ year
2.89

2.58

3.2.3. Average bust size
Research results in Table 3.7 show that average bust size of male pupils
increased from a range of 62.88-63.96 cm to a range of 77.32-77.48 cm, an
average increase of 2.23 to 2.43cm/year. Similar to the weight development,
average bust size of female pupils increased from a range of 60.02-63.02 cm
at 11 years old to a range of 74.57-74.95 cm at 17 years old, an average
increase of 1.97 to 2.43 cm/year. The speed of increasing average bust size
by age is unequal. The fast period of increasing average bust size of pupils
takes place at the same time with period of increasing weight and later than
period of increasing height. Overall, average bust size of Kinh pupils is larger
than Muong and San Diu pupils in most of the age groups with the significant
level of 5 percent.

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3.2.4. BMI
The data in Table 3.8 show that BMI of male pupils and female pupils
increases with age, increasing by an annual average of about 0.22 to 0.33
kg/m
2
for male and 0.43 to 0.46 kg/m
2
for female.
Results in Table 3.9 show that pupils who have ordinary situation
account for the majority (84.55% male and 84.83% female), the number of
pupils who have malnourished situation account for a relatively high

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98.75 mmHg and 99.81-101.01 mmHg to the ranges of 109.14-109.35
mmHg and 111.14-111.74 mmHg, respectively. The period that has fastest
increase systolic blood pressure in all three ethnic groups is from 13 to 14
years old and for female pupils from 12 to 13 years old.
In all three ethnic groups, systolic blood pressure of female pupils has
a higher value than that of male pupils at the same age (p<0.05).
3.3.1.3. Diastolic blood pressure
Diastolic blood pressure increases at the age of 11 from a range of
57.85-58.82 mmHg for male pupils and from a range of 59.83-60.68 mmHg
for female pupils. At the age of 17, the pressure increases from a range of
68.17-69.29 mmHg for male pupils and from a range of 69.44-70.39 mmHg
for female pupils. The period that has the fastest increases diastolic blood
pressure in all three ethnic groups is from 13 to 15 years old for male pupils
and from 12 to14 years old for female pupils.
In the same age, diastolic blood pressure of female pupils has a higher
value than that of male pupils in all three ethnic groups (p<0.05).
When comparing the diastolic blood pressure and systolic blood
pressure of pupils, we found no statistical difference.
3.3.2. Some respiratory function indicators
3.3.2.1. The respiratory parameters
+ Respiratory frequency
The results in Table 3.14 show that the respiratory frequency of Kinh,
Muong and San Diu pupils reduces from the age of 11 to 17, although the
decline between ages is very low (an average of 0.44 to 1.32 beats/minute/year).
Since 17 years old, respiratory frequency of pupils is equivalent to that of adults.
The period that respiratory frequency of female pupils rapidly decrease (12 - 14
years old) is 1 year earlier than of male pupils (from the age of 13 to 15). In
general, there is no difference in respiratory frequency between male and
female pupils in the three ethnic groups.

n
X
± SD
Increase
Kinh
11
120
2.02  0.17
-
121
1.77  0.15
-
0.25
<0.05
12
120
2.17  0.22
0.15
121
2.04  0.12
0.27
0.13
<0.05
13
121
2.47  0.22
0.30

0.36
<0.05
17
118
3.52  0.16
0.05
120
3.19  0.22
0.08
0.33
<0.05
Muong

11
84
1.91  0.18
-
81
1.63  0.21
-
0.28
<0.05
12
83
2.11  0.12
0.20
84
1.97  0.17
0.34
0.14

3.37  0.19
0.16
86
3.07  0.19
0.10
0.30
<0.05
17
85
3.49  0.22
0.12
83
3.11  0.26
0.04
0.38
<0.05
San Diu

11
60
1.87  0.21
-
61
1.57  0.21
-
0.30
<0.05
12
62
1.98  0.24

0.34
0.24
<0.05
16
60
3.23  0.24
0.22
59
2.92  0.18
0.15
0.31
<0.05
17
60
3.35  0.25
0.12
61
3.03  0.14
0.11
0.32
<0.05
+ Forced Vital Capacity (FVC)
Results in Table 3.16 show that, FVC increases at age 11 from 1.77 to
1.92 liters for male pupils and 1.45 to 1.65 liters for female pupils. Since 17
years old, it is from 3.24 to 3.42 liters for male pupils and 2.92 to 3.08 liters
for female pupils. There is an average increase of 0.25 to 0.26 liters/year for
male pupils and 0.24 to 0.25 liters/year for female pupils. The fastest
increasing piriod of FVC in all three ethnic groups is at 13 to 15 years old
for male pupils and 12 to 14 years old for female pupils. In general, the
FVC of male pupils is greater than that of female pupils (p<0.05).

3.3.2.2. Some respiratory indicators
+ The Tiffeneau (FEV
1
/VC)
Results in Table 3.18 show that the Tiffeneau of male pupils changes
from 80.80 to 88.89% and that of female pupils changes from 80.32 to
88.20% depending on ethnic groups. In terms of gender, the Tiffeneau of
male and female pupils are equal in the same group of age.
+ The Gaensler (FEV
1
/FVC)
Results on Gaensler are presented in Table 3.19. Gaensler index of
male pupils ranges from 85.57 to 91.46% and that of female ranges from
84.89 to 93.47% depending on ethnic groups. Gaensler index of pupils in
ethnic groups has no statisticcal difference.
+ The Demeny
Results in Table 3.20 show that the Demeny of male pupils ranges
from 63.33-76.52. The Demeny of female pupils ranges from 54.74-75.09
depending on ethnic groups.
3.3.3. Reflection time of feeling - movement
3.3.3.1. Reflection time of visual - movement
Reflection time of visual - movement of pupils decreases from 11 to
14 years old and stabilized at the age of 15 to 17. For male pupils, reflection
time of visual - movement ranges from 357.11 to 369.17 ms at age of 11. At
14 years old, it decreases from 315.12 to 365.57 ms. From 15 to 17 years
old, it ranges from 316.47 to 342.65 ms. For female pupils, reflection time
of visual - movement ranges from 368.49 to 383.25 ms at the age 11. At 14
years old, it decreases from 325.26 to 355.31 ms. From 15 to 17 years old, it

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2.27 points/year. These indicators of female pupils of Kinh, Muong and San
Diu ethnic groups are 95.38, 92.53 and 91.27 at the age of 11 and at the age
of 17 years old, are 107.83, 103.19 and 102.29 points. There are increases of
2.08, 1.78 and 1.84 points per year on the average. In terms of gender, IQ of
male and female pupils are not different. IQ of Kinh pupils is higher than
those of Muong and San Diu pupils with p<0.05.

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Table 3.23. IQ index of pupils by age, ethnics and gender

Ethnic
group

Age
IQ index (point)

21
- XXp(1-2)
Male (1)
Female(2)
n
X
± SD
Increase
n
X
± SD

-0.75
>0.05
14
122
102.41  14.99
2.10
120
102.92  16.25
1.86
-0.51
>0.05
15
121
104.85  15.01
2.44
119
104.34  14.87
1.42
0.51
>0.05
16
117
106.79  15.94
1.94
120
105.80  15.11
1.46
0.99
>0.05
17

>0.05
12
83
93.87  15.09
1.96
84
94.78  15.00
2.25
-0.91
>0.05
13
82
95.16  15.00
1.29
86
95.67  14.87
0.89
-0.51
>0.05
14
84
97.97  15.09
2.81
84
98.17  14.88
2.50
-0.20
>0.05
15
81


98.04

15.64
1.78
0.13
>0.05
San Diu

11
60
90.00  14.88
-
61
91.27  14.91
-
-1.27
>0.05
12
62
92.02  15.13
2.02
58
92.38  14.91
1.11
-0.36
>0.05
13
59
94.83  14.88

1.79
0.16
>0.05
17
60
103.62  15.12
1.61
61
102.29  14.94
0.44
1.33
>0.05
Average
97.16

15.45
2.27

97.44

15.68
1.84
-0.28
>0.05
3.4.1.2. Distributing pupils by intellectual levels
The distributing of pupils regarding intellectual levels in all three ethnic
groups Kinh, Muong and San Diu is a standard distribution and no pupils are
unintelligent. There is no difference in intellectual capacity by gender.
Percentage of pupils who have high intelligence level increases by age.
Especially, there is no high school pupil with level VI intelligence. Meanwhile,

The growth rate of weight, height and brust size of Kinh, Muong and San
Diu pupils are unbalanced. At the early stage, height increases faster than weight,
weight increases faster than height and brust at the next stage. This fact leads to
an increase in the pignet index of pupils at early stages and a decrease at later
stages in all three ethnic groups Kinh, Muong and San Diu.
In the studied indicators, VC, FVC, FEV1, systolic blood pressure and
diastolic blood pressure indicators increase by age, some other indicators,
such as breathing frequency and heart rate, decrease by age for pupils in all
three ethnic groups. VC, FVC and FEV1 coefficient increases greater than
arterial pressure. Thus, in the course of child development, the development
of the organs and organ systems are uneven in both structure and function.
The increasing time of VC, FVC, arterial blood pressure coindences with
the increasing time of height of pupils.
Results in Table 3.28 show that studied respiratory parameters
increase with height and age. For Kinh group, H coefficient is the highest,
followed by Muong group and the lowest one is that of San Diu group.
Correlating coefficies of the VC, FVC and FEV1 range from 0.874 to 0.985

17
indicating that the parameters are closely related to age and height, the
regression fomula: VC = aH + bA + c.
Table 3.28. Recurrent equation of lung function parameters of pupils
Ethnic
groups
Data
Units
Male
Female
%
0.2A + 84.923
0.347
-0.238A + 92.955
0.309 Muong
VC
liter
0.778H + 0.2A - 1.893
0.943
1.058H + 0.214A- 1.979
0.874
FVC
liter
0.824H + 0.243A – 2.006
0.941
0.946H + 0.214A- 1.950
0.874
FEV1
liter
0.722H + 0.226A – 1.937
0.943
0.564H + 0.215A- 1.701
0.905
FEV1/VC
%
-0.4295A + 72.047
0.212

%
0.429A + 80.625
0.172
0.410A + 79.719
0.159
FEV1/FVC
%
0.02A + 90.018
0.208
-0.238A + 92.955
0.109
3.5.2. Relationship between IQ and short-term memory
The relationship between IQ and short-term memory of pupils in all three
ethnic groups is a positive linear relationship with r ranges from 0.602 to 0.815
and the regression fomula Y1 = a1IQ + b1 với a1>0.
3.5.3. Relationship between IQ index and concentration
Relationship between IQ and concentration of pupils in all three ethnic
groups is a positive linear relationship with r ranges from 0.682 to 0.785 and
the regression fomula Y2 = a2IQ + b2 với a2>0.
3.5.4. Relationship between IQ index and Sersor-motor reflection
Relationship between IQ index and visual - motor reflection and auditory -
motor reflection of pupils of pupils in all three ethnic groups is a negative linear
relationships with r ranges from -0.832 to -0.903, respectively.
CHAPTER 4. DISCUSSION
4.3. PUBERTY OF PUPILS
Changes in morphology, function closely associate to puberty period
of pupils. From the study, it can bee seen that puberty period of female
pupils in Phu Tho and Vinh Phuc provinces ranges from 12 years and 10
months to 13 years and 4 months. Age of first menstruation of Kinh pupils
is earlier than those of Muong and San Diu pupils. In our opinion, in

average annual increase of 2.89 to 3.12 kg for male and 2.58 to 2.67 kg for female.
Weight of pupils increases unevenly, rising fastest in puberty, from 14 to 16 years
old for male and from 13 to 15 years old for female. In general, weight of male
increases fasster than that of female. However, in the period from 11 to 14 years old,
the growth rate of this index of femal is faster than that of male and in the period from
14 to 17 years of age, weight of male increases faster and reaches higher values
compared with female’s. Weight of Kinh pupils is higher than those of Muong and
San Diu pupils. This happens because of economic conditions of Kinh ethnic group
is better than those of Muong and San Diu Ethnic groups.

19
Weight of the pupils in the study is higher than that of pupils in the studies
of “Biological constant of Vietnamese people”, by Tran Van Dan and coworkers,
Tran Dinh Long and his coworkers and Dao Huy Khue and equivalent to that in
studies of Tran Thi Loan and Do Hong Cuong. In our opinion, this is partly due to
genetic factors and partly because ethnic pupils are living and studying at Ethnic
boarding schools.
Weight and height changes leading to changes in BMI. BMI of Kinh, Muong
and San Diu pupils gradually increases from 11 to 17 years old. This result is
consistent with the results in the “Biological value of ordinary Vietnamese in the
90s - the twentieth century” and in studies of Tran Dinh Long, Tran Thi Loan, Do
Hong Cuong. Based on Classification standard, BMI of children from 2 to 20 years
old by WHO in 2006, the majority of pupils have nomal physical strength (84.55%
for male and 84.85% for female), followed by pupils who are malnourished
(14.80% for male and 14.94% for female). Pupils at risk of obesity account for a
very low rate and there is no puffy pupils. This shows that nutrition level of Kinh,
Muong and San Diu pupils is still low and the diet does not ensure balanced
development for the body. However, compared to pupils about two decades ago,
physical strength of pupils in our study is better.
4.2.2. Average bust size and Pignet index

time of puberty. This is probably influenced by changes in sympathetic and
parasympathetic nerve activities during puberty. Heart rate of female pupils is
always higher than that of male pupils at most age groups. This is consistent with
study results by DoanYen, Tran Thi Loan and Do Hong Cuong. There are
differences in heart rate among pupils of different ethnic groups.
The increasing influence of parasympathetic nervous activities on
circulatory system is also reflected by the change of blood pressure with
ages. From the study, it can be seen that arterial pressure increases by
pupil’s age and the certain levels depend on gender. The study results show
that blood pressure depends on the momentum of the heart, vascular
elasticity and activities of organs in the brust size.
4.3.2. Respiratory function indexes
Respiratory frequency gradually decreases by age. We think the change in
respiratory frequency intimately related to changes and regulation of nerves in
puberty period for operations of organs in the body. The phenomenon of
decreasing respiratory frequency by ages may be reported in earlier studies. The
phenomenon of decreased respiratory frequency is closely related to gas
exchange in one breath. The study shows that pupils' vital capacity increases
from 11 to 17 years old. Similar results can be seen in the previous studies. Vital
capacity of male pupils is higher than that of female pupils, Kinh pupils' vital
capacity is higher than those of Muong and San Diu pupils. However, changes in
living conditions lead to physical changes, so vital capacity of the pupils in our
study may slightly differ compared to that in previous studies. When being
compared with recent studies, there is no. We think this difference is because
vital capacity correlates closely and agreeably with height.
The change in FVC is similar to those in VC, FVC of Kinh pupils has
maximum value, followed by those of Muong and San Diu pupils. This
difference is probably infuenced by morphological characteristics and physical
strength of pupils which has a linear relationship with lung function index.


positive and untight correlation with age. In comparison with other studies,
it can be seen that Tiffeneau index of pupils in our study is equivalent to the
results of Do Hong Cuong and “Biological value of ordinary Vietnamese in the
90s - the twentieth century”.
Gaensler index of male pupils ranges from 85.57 to 91.46% for male
and from 84.89 to 93.47% for female. Gaensler index of Kinh, Muong and
San Diu changes a little by ethnic groups. Gaensler index has a negative and
untight correlation by age. In comparision with other studies, Gaensler index
of pupils in our study is lower than those in studies of Do Hong Cuong and
“Biological value of ordinary Vietnamese in the 90s - the twentieth century”.
To determine respiratory function in a comprehensive manner, we define
Demeny index (VC/weight). This index ranges from 63.33 to 76.52 for male and
54.74 to 75.09 for female depending on ethnic groups. In general, this index of
male is higher than that of women in most studied age groups. Compared to
other studies, it can be seen that Demeny index of pupils in our study is lower
than that of study of Do Hong Cuong and comparable to study results by Trinh
Binh Dy and his coworkers and Do Dinh Huong.
Compared to other studies, respiratory index of pupils in our study is higher
than the figures in "Biological constant of Vietnamese people”, study results by Doan
Yen and equivalent to study results of Tran Thi Loan, Do Hong Cuong, “Biological
value of ordinary Vietnamese in the 90s - the twentieth century”.

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Based on respiration index, it can be said that currently, physical
strength of pupils tends to be better than that in two decades ago.
4.3.3. Sensor-motor reflection time
Reflection is the physiological norm allowing to evaluate mobilization of
pupils. The research results show that during the period from 11 to 14 years old,
sersor - motor reflection time of pupils gradually decreases and become more
stable between 14 to 17 years old. This happens since, from 14 to 15 years old,

proportion of male and female pupils who have the same intellectual level is

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not significantly different. This observation is consistent with the results
from Ngo Cong Hoan, Ta Thuy Lan and Vo Van Toan, Tran Thi Loan. This
proves that intellectual development of pupils depends on ability to
accumulate knowledge and operational methods of brain. Therefore, to
develop intellectual capacity, it is necessary to improve knowledge and
thinking. To implement these processes, we need to develop the ability to
remember. In fact, the ability to remember of pupils increases by age, rising
rapidly in the period from 11 to 14 years old. However, at the age of 15 to 17,
when the nervous system has developed relatively completed, the ability to
memorize trends to be stable. Visual memory of the pupils is always higher
than auditory memnory. This proves that ability to view for memorizing of
pupils is better than ability to hear for memorizing. This is a testament to the
saying "Observations is the best teacher". This is the basis for an innovative
teaching method which is the improvement from imparting knowledge to active
teaching at schools in particular and in education sector in general. The results
of our study also shows that there is no difference regarding memorize ability
between male and female pupils at the age from 11 to 17 in retention. This is
also a basis for the difference in intellectual activity by gender.
To remember well, it is necessary to concentrate. From our study, we
can see that pupils' attention changes by ethnic and age groups. The ability
to concentrate is an important indicator to determine complete development
of the nervous system in different stages of development. Like intellectual
capacity, ability to concentrate depends on living and studying conditions.
Therefore, ability to concentration of pupils in different ethnic groups is
different. Similar results can be seen in the previous studies.
4.5. RELATIONSHIP AMONG BIOLOGICAL INDEX OF PUPILS
4.5.1. The relationship between physical and functional indicators

ethnic groups is a positive linear relationship with r ranges from 0.682 to 0.785.
There is a collative and tight relationship among intellectual capability and
concentration ability and the regression fomula Y2 = a2IQ + b2 with a2>0. In
which a2 is a ratio of IQ and b2 is a constant. The ratio of IQ in all correlations
are positve and different within ethnic groups.
4.5.4. Relationship between IQ index and Sersor-motor reflection
Relationship between IQ index and visual - motor reflection and auditory -
motor reflection of pupils of pupils in all three ethnic groups is a negative linear
relationships with r ranges from -0.832 to -0.903, respectively. The relationship
between intellectual capability and reaction time of senses - exercise is close and
inversely linear correlation and the regression fomula T = mIQ + n with m<0. In which
T is the reaction time of sensor - motor and m is the coefficient of IQ and n is constant.

CONCLUSION
1. Puberty period and morphological indexes-physical, physiological function
indexes
- Kinh, Muong and San Diu schoolgirls reach puberty time at 13 years
old and 12 months, 13 years old and 2 months and 13 years old and 4 months,

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respectively. Kinh, Muong and San Diu schoolboys reach puberty time at 14
years old and 5 months, 14 years old and 2 months and 14 years old and 7
months, respectively.
- Schoolboys’ height gradually increases from 133.97 cm at the age of 11 to
164.45 cm at the age of 17. Especially when schoolboys are at the range from 13 to
15 years old, their height increases with the highest speed. Schoolgirls’ height
gradually increases from 135.03 cm at the age of 11 to 156.25 cm at the age of 17.
Especially when schoolgirls are at the age of 12-14, their height increases with the
highest speed. Girls’ height is greater than boys’ height at the age of 11 to 14, but
the height of schoolboys is greater than that of schoolgirls at the age of 15 to 17.