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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
CLASSROOM INTERACTION PATTERNS AS
CORRELATES OF SENIOR SECONDARY
SCHOOL STUDENTS’ ACHIEVEMENT IN
CHEMISTRY IN AWKA EDUCATION ZONE
Stella O. Agbasi
+2347068993664
stellaagbasi@gmail.com
Science Education Department
Nnamdi Azikiwe University, Awka, Anambra State,
Nigeria
Jane C. Madichie
Federal College of Education (Technical), Umunze,
Anambra State, Nigeria
Abstract
The technique of teaching chemistry to students is one of
the determining factors towards their achievement. Thus,
the study investigated classroom interaction patterns as
correlates of secondary school students’ achievement in
Chemistry in Awka Education zone. Five research
questions and three hypotheses guided the study. The study
adopted a correlational survey design. The sample
consisted of 450 (212 males and 238 females) senior
secondary one students and 12 (5males and 7 females)
chemistry teachers drawn from 12 selected secondary
schools in the area. Science Interaction Category (SIC)
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
and Chemistry Achievement Test (CAT) were developed,
validated and used for data collection. Each teacher was
observed three times and the interaction patterns coded
using a coding sheet containing the SIC. At the end of the
observational period, the CAT was administered on the
students. Frequencies, percentage, mean, standard
deviation and Pearson product moment correlation were
used for data analysis. The result showed that the
percentages of teacher talk, student talk and silence were
59.6%, 37.6% and 2.8% respectively. The result showed
negative and significant relationship between teacher talk
and students ‘achievement; positive and significant
relationship between student talk and mean achievement
scores of students but there is no relationship between
period of silence and mean achievement scores of students
at 0.05 significant levels. The study recommended that
teachers should establish high level of student talk through
initiation and response as it promotes involvement and
enhances achievement.
Keywords: Classroom Interaction Patterns, Chemistry,
Academic Achievement, Senior Secondary School
Introduction
In contemporary Nigeria, greater emphasis is being placed
on industrial and technological development. As a result,
students are being encouraged to take up science related
subjects. Within the content of science education,
chemistry has been identified as a very important school
subject and its importance in scientific and technological
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
development of any nation has been widely reported
(Olatoye, Aderogba & Aanu, 2011). Chemistry is one of
the subjects that cut across all the sciences. In Nigeria‟s
march toward scientific and technological advancement,
nothing short of good performance is needed in chemistry
at all levels of schooling. Unfortunately performance of
students in chemistry has not improved (Adedeji, 2007).
Some factors have been identified as the cause of students‟
under-achievement in chemistry. These factors include
ineffective teaching methods and strategies, poor
motivation of students, ill-equipped laboratories, poor
students‟ attitude to science and students‟ laziness, (Offiah
& Akusoba, 2009). It is necessary to find ways of
ameliorating these noted impeding factors in order to boost
achievement in chemistry. It is thought that one of the
ways of enhancing achievement is by making teachers
know the classroom interaction pattern that is adequate for
their students.
Classroom interaction, therefore, is the talk that occurs
between teachers and students and among students (Best &
Addison, 2000). It is the primary medium through which
learning occurs in the classroom that is any kind of
classroom, be it history or chemistry classroom. According
to Kouicem (2012), classroom interaction or classroom
behaviour describes the form and content of behaviour or
social interaction in the classroom. Interaction in the
classroom is an essential part of teaching-learning process.
The classroom climate is built up by the patterns of
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
interaction between teachers and students‟ verbal
exchange, asking questions, responding and reacting.
Classroom interaction during the teaching- learning
process could be verbal or non-verbal behaviors. The most
important factors in a classroom situation are the
interactive exchanges initiated by teachers and students. It
is considered as a productive teaching techniques and it
refers to the whole range of activities and experiences
through which the teacher, curriculum materials and the
learners interact (Abe & Bello, 2019)
Classroom interaction is important because interaction is
the essential criteria of classroom pedagogy. According to
Hussain (2011), classroom interaction promotes
involvement, enhances learning and motivates the
students. Hussain added that it promotes a shift from
teacher centered to student centered environment.
According to the author, indicated teachers-students
interaction through classroom discussion and other forms
of interactive participation is foundational to deep
understanding and is related to students‟ achievement.
Teachers establish the pattern of general conduct during a
lesson, while on their part students establish certain types
of behavior to coincide with this pattern (Kalu, 2008).
According to Thompson and Anderson (2008), one of the
most basic characteristics of a good teacher is the ability to
establish adequate interaction in the classroom and most of
the observed stresses in the classroom come from lack of
desired interaction. Talking in itself cannot be considered
as interaction, interaction is all of the ways in which action
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
and reaction among individuals is organized. Ifamuyiwa
and Lawani (2009) further added that observed classroom
interaction could be divided into teacher talk and student
talk.
Classroom activity or interaction patterns can be described
as teacher talk, student talk and period of silence or
confusion. Teacher talk is further classified as direct and
indirect influence (Flanders in Sahlbery, 2010). Indirect
influence has subcategories which are accept feeling,
praise and encourage, accepts and uses idea of students
and ask question. Direct influence also has subcategories,
which are lecturing, giving directions, criticizing or
justifying authority; Student talk could be classified as
response and initiation; Period of silence or Confusion is
an integral part of classroom interaction and a key concept
of the way we interact. It functions as a means of reticence
and reflection (Onwiodiokit & Oranu, 2012).
Academic achievement is not just dependent on
individual abilities and aspiration, but also on the patterns
of classroom interaction (Awal, 2010). Classroom
interaction can thus enhance or diminish the behaviour that
leads to achievement. The classroom verbal pattern created
by a teacher has become an important factor in the
teaching- learning process, and therefore it should be
identified and utilized for optimal learning.
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Statement of the Problem
Today in Nigeria, poor students achievement has been
written about and discussed in conferences, suggestions
have been made on the way forward especially by
improving methods of teaching. Evidence seem to show
that the use of different methods have led to very little if
any improvement. Students‟ poor performance in
chemistry has been a source of worry to teachers, guidance
and counselors, parents, academicians and the society at
large. The problem of poor performance or achievement in
chemistry has persistently occupied the mind of teachers in
secondary school. Factors such as parental influence,
ineffective teaching strategies, poor motivation of students
and ill equipped laboratories have been identified as the
cause of students‟ achievement by various authors. While
these factors have been well researched, little attention has
been paid to classroom interaction patterns. This study was
to establish if there is any relationship between classroom
interaction patterns and senior secondary school students‟
achievement in chemistry.
Purpose of the Study
The purpose of the study was to determine the relationship
between classroom interaction patterns and students‟
achievement in chemistry. Specifically, the study sought to
a. Identify the patterns of interaction in an observed
chemistry classroom.
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
b. Determine the amount of teacher talk, student talk and
period of silence or confusion in an observed chemistry
classroom.
c. Find whether the relationship between classroom
interaction pattern and the mean achievement scores of
the students is significant.
d. Determine the relationship between the amount of
teacher talk (direct and indirect influence) in the
classroom and students‟ achievement
e. Determine the relationship between the amount of
student talk (response and initiation) and students‟
achievement
f. Determine the relationship between the period of
silence or confusion in the classroom and students‟
achievement
Research Questions
To investigate the problem of this study, the following
research questions guided the study;
1. What are the patterns of interaction in an observed
chemistry classroom?
2. What are the amount of teacher talk, student talk and
period of silence or confusion in an observed chemistry
classroom?
3. What is the relationship between the amount of teacher
talk (direct and indirect influence) in the classroom and
students‟ achievement?
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
4. What is the relationship between the amount of student
talk (response and initiation)
and students‟
achievement?
5. What is the relationship between the period of silence
or confusion in the classroom and students‟
achievement?
Hypotheses
To achieve the purpose of this study, the following
hypotheses were tested at 0.05 level of significance
1. There is no significant relationship between the amount
of teacher talk (direct and indirect influence) and mean
achievement scores of students in chemistry.
2. There is no significant relationship between the amount
of student talk (response and initiation) and mean
achievement scores of students in chemistry.
3. There is no significant relationship between the period
of silence or period of confusion in the classroom and
mean achievement scores of students in chemistry.
Method
Correlation survey was used to generate empirical data
needed for the study. Correlation survey was used because
the study aims at determining the relationship between
classroom interaction patterns and students‟ achievement
in chemistry in Anambra state secondary schools. The
population is 4,419, made up of 65 chemistry teachers and
4,354 senior secondary one (SS1) students, found in the 61
government owned secondary schools in Awka Education
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Zone of Anambra state. The sample of the study consisted
of 12 chemistry teachers and 450 SS1 students from 12
schools. Two instruments were used to collect data for the
study, namely; Science Interaction Categories (SIC) and
Chemistry Achievement Test (CAT). SIC had 10
categories and was used to code and analyze the
interaction patterns during chemistry lessons in the
selected schools used for the study. It is an adaptation of
Flanders‟s (1970) observation system designed to code
teachers‟ and students‟ behavior during science lessons.
CAT had 20 items assessed on a multiple choice scoring
scale. It was based on the following topics taught in SS1
when the data were collected for the study: Chemical
industries, particulate nature of matter, physical and
chemical changes and separation techniques for mixtures.
Data collection was based on classroom observation. Data
for the study were collected during the first term of the
secondary school academic session and from the 2nd week
of the term.
After two-week in school training session by the
researcher and two assistants on how to use the SIC in
coding classroom interaction during chemistry lessons.
Each of the 12 selected teachers was observed during their
normal class teaching and interactions coded using a
coding sheet containing the SIC. These teachers were
observed for three lesson periods spaced over a period of
eight weeks, when the topics were taught in the schools.
The teachers were observed. Records of activities of the
teachers and students in the classroom including period of
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
silence were taken every 5mins period of interaction, in
each lesson, that is 1-5mins, 6-10mins,11-15mins,1620mins, 21-25mins, 26-30mins, 31-35mins, 36-40mins
and in cases of ambiguity or when two events occurred
simultaneously both events were recorded. Therefore
eight entries for every 40 minutes lesson were recorded.
Each observation took a coding sheet. At the end, the
records from the 12 coding sheets for the 12 observations
were collated. Thus, in scoring the instrument, the
frequency of a particular category in a period was
considered. CAT was also administered on the 450
students. The students comprised 212 males and 238
females. The average age of the students is 15.72. Their
scores were duly recorded.
Data generated with the instruments was analyzed using
frequency, mean, standard deviation, percentage, Pearson
Product Moment Correlation for measures of relationship.
The hypotheses were tested at 0.05 level of significance.
Research question 1: What are the patterns of interaction
in an observed chemistry classroom?
The science interaction category (SIC) was used to answer
Research question 1.
Patterns of interaction in an observed chemistry
classroom
Teacher talk:
Accepting, clarifying‟ discussing, praising, repeating
words, praising, encouraging, display question,
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
encouraging, giving information, joking, referential
questions, explaining, correct mistakes, request, giving
direction, criticizing and smiling.
Student talk:
Accepting, affirmative answer, negative answer, question,
request, surprising, laughter and borrowing.
Silences
Research Question 2: What are the amount of teacher
talk, student talk and period of silence or confusion in an
observed chemistry classroom?
The SIC was used to answer research question 2
Table1: Frequency and Percentage of teacher talk,
student talk and period of silence
Interaction patterns
Indirect Teacher Talk
Accepts feelings
Praises/encourages
Accepts and uses ideas
Ask questions
Total
Direct Teacher Talk
Lectures
Gives direction
Criticizes or Justifies
authority
Frequency Percentage (%)
22
31
23
176
252
2.1
3
2.2
17.1
24.4
223
64
47
21.4
6.2
4.6
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Manipulates apparatus
Supervises
Total
13
18
365
1.8
1.7
35.2
Student Talk
Responses
142
13.8
Initiates talk
36
3.5
Questions
28
2.6
Experiments
Read, writes and draws
96
9.3
Student-Student
87
8.4
interaction
Total
389
37.6
Silences
29
2.8
Grand Total
1032
100
Table 1 indicates the frequency and percentage of
classroom interaction patterns. It shows that the percentage
of teacher talk is 59.6%, with indirect as 24.4% and direct
talk as 35.2%; student talk (response and initiation) is
37.6% and silence is 2.8%. The percentage of teacher talk
is more than that of student talk and silence.
Research Question 3: What is the relationship between
the amount of teacher talk (direct and indirect influence)
and students‟ achievement in chemistry?
The SIC and CAT were used to answer research question
3.
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Table 2: Mean, Standard deviation and Pearson
correlation of the amount of teacher talk and students’
achievement.
Variable
N
X
SD
Teacher talk
12
51.42
6.02
r
-0.61
Students‟ achievement
12
38.59
2.13
The result as shown in Table 2 shows that the mean of
teacher talk is 51.42 and standard deviation is 6.02 and
that of students‟ achievement score is 38.59 and the
standard deviation is 2.13.The Pearson product moment
correlation coefficient (r) is -0.61. This indicates a high
value of correlation. This also indicates that there is a
strong negative relationship between teacher talk and mean
achievement scores of students in chemistry. This means
that as the amount of teacher talk is increasing, the
students‟ achievement scores is decreasing.
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Hypothesis 1: There is no significant relationship
between the amount of teacher talk (direct and indirect
influence) and mean achievement scores of students in
chemistry.
Table 3: The correlation between teacher talk and
mean achievement scores of students
Variable
N X
Teacher talk 12 51.42
SD
r
Sf P
Decision
6.02
-0.61 0.05 0.04 Reject Ho
Achievement
scores
12 38.59 2.13
The Pearson Correlation coefficient statistics in table 3
shows P value of 0.04 which is less than 0.05 0f
significance (2 tailed). That is P<0.05. Therefore, the null
hypothesis is rejected and the alternative hypothesis is
upheld. This means that there is significant relationship
between the amount of teacher talk (direct and indirect
influence) and mean achievement scores of students in
chemistry.
Research Question 4: What is the relationship between
the amount of student talk (response and initiation) and
students‟ achievement?
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Table 4: Mean, Standard deviation and Pearson
correlation of the amount of student talk and students’
achievement.
Variable
Student talk
N
12
Achievement
Scores
12
X
32.42
38.59
SD
6.05
r
-0.76
2.13
Table 4 shows the mean of the amount of student talk is
32.42 and the standard deviation is 6.05. That of students‟
achievement score is 38.59 and the standard deviation is
2.13.The Pearson correlation value (r) is -0.76. This
indicates a high value of correlation. This indicates that
there is a strong relationship between the amount of
student talk and mean achievement scores of students in
chemistry.
Hypothesis 2: There is no significant relationship between
the amount of student talk (response and initiation) and
mean achievement scores of students in chemistry.
Table 5: The correlation between student talk and
achievement scores
Variable
N
X
SD
r Sf
P
12 32.42 6.05
-0.76 0.05 0.01
Achievement 12 38.59 2.13
Scores
Decision
Student talk
50
Reject HO
South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
The table 5 shows that P value is 0.01 which is less than
0.05 0f significance (2 tailed). That is P<0.05. Therefore,
the null hypothesis is rejected and the alternative
hypothesis is upheld. This means that there is significant
relationship between the amount of student talk (response
and initiation) and mean achievement scores of students in
chemistry.
Research Question 5: What is the relationship between
the period of silence or confusion
and students‟
achievement in chemistry?
Table 6: Mean, Standard deviation and Pearson
correlation of the period of silence and students’
achievement.
Variable
N X
SD
Silence
12 2.42 1.88
r
-0.18
Students‟
achievement 12
38.59 2.13
Table 6 shows the mean of period of silence to be 2.42 and
standard deviation as 1.88. That of students‟ achievement
score is 38.59 and the standard deviation is 2.13. Pearson
correlation coefficient (r) value is -0.18, this indicates a
very low value of correlation. This means that there is no
relationship between the period of silence and mean
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
achievement scores of students in chemistry. This also
means that increase or decrease in the period of silence
does not have an impact on the mean achievement scores
of students.
Hypothesis 3: There is no significant relationship between
the period of silence and mean achievement scores of
students in chemistry.
Table 7: Correlation between period of silence and
mean achievement scores of students
Variable N X
Silence 12 2.42
SD
1.88
r
Sf
P
Decision
-0.18 0.05 0.58 Accept HO
Achievement 12 38.59 2.13
scores
The table shows that P value is 0.58 which is greater than
0.05 (P>0.05). This indicates that the correlation is not
significant at 0.05(2 tailed). Therefore the null hypothesis
is accepted and upheld. This means that there is no
significant relationship between the period of silence and
mean achievement scores of students in chemistry.
Discussion
From the result of this study in table 2, the amount of
teacher talk (direct and indirect influence) is 59.6%. This
result is in agreement with the views of Zaheed and
Moenikia (2010) who stated that the share of teacher talk
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
is 57.1%. The analysis also revealed that as the amount of
teacher talk is increasing, the students‟ achievement scores
are decreasing. This is due to the fact that teacher talk
entails active involvement of teachers and passive
involvement of students. Teaching and learning process
that has been based only on teacher talk as a pattern of
interaction, have been shown by Zaheed etal to be
relatively ineffective on the students‟ ability to retain
important concept and has made learning to be passive
rather than active. Maduewesi and Ezeani (2012) in their
contribution asserted that teacher talk does not encourage
creativity because students are reduced to mere passive
listeners and not thinkers.
Conclusion
The study has provided insight into the significant
relationship between teacher talk, student talk and
improved academic achievement among students.
Classroom interaction that do not create integral opening
for practicing or applying what is taught, will be reduced
to mere rote learning for academic achievement and what
is assumed to have been learnt may not be applied
elsewhere. Therefore, in line with the best practices in
classroom interaction, some measure of democracy should
become part of the classroom, by giving students some
powers to control their own learning. This can be achieved
through allowing the students to be actively involved in
the learning process by increasing the amount of student
talk (response and initiation) and reducing the amount of
teacher talk(direct and indirect influences).
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
This study has also created the awareness to chemistry
teachers who hitherto did not have the learner at centre
during lessons but totally dominate the class. Too much
teacher talk therefore reduces students „achievement but
practicing student centered learning through active student
talk is most rewarding.
Recommendations
Based on the findings of this study, the following
recommendations were made:
1. Teachers should establish high level of student talk
through initiation and response as it promotes
involvement and enhances achievement.
2. Teachers should also ask questions that will encourage
students‟ participation in chemistry teaching.
3. Teachers should provide chances to the student to
participate in teaching and learning process and start
classroom discussion.
4. Ministry of education (Federal and State) should
organize seminars and workshops to keep teachers
(chemistry teachers inclusive) abreast of the application
of classroom interaction patterns for instructional
delivery.
5. Teachers should endeavor to make teaching more
learner‟s centered by encouraging student talk. This
will improve achievement in science subjects,
including chemistry.
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South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
References
Abe, R.T & Bello,G. (2019). Patterns of classroom
interactions and students reactions toward study
barriers in Biology lessons. Lonaka JoLT, 10 (1),
82-93.
Adedeji, T. (2007). The impact of motivation on students‟
academic achievement and learning outcomes in
Mathematics among secondary school students in
Nigeria. Ogun State. Journal of Mathematics,
Science and Technology Education, 3(2), 149-156.
Adesoji, F. & Olatunbosun S.M (2008). Student, teacher
and school environment factors as determinants of
achievement in senior secondary school chemistry
in Oyo State, Nigeria. Journal of International
Social Sciences, 1(1), 56-78.
Awal, H. (2010).Classroom interaction in English in
mathematics and science classes. Retrieved from
http:acanp.bravehost.com.
Bruce, C.D. (2010).Student interaction in Mathematics
classroom. Journal of Education, 1(4),121-134
Fakeye, D. O. (2007).Teacher questioning behavior and
classroom interaction patterns. Journal Humanities
and Social Sciences, 2,127-131.
Hussain, L. (2011). The effects of classroom interaction on
students‟ achievement at secondary school level.
Mediterranean Journal of Social Sciences, 2(3),123134
55
South Eastern Journal of Research and Sustainable Development (SEJRSD).
Vol. 3 (1), March, 2020. ISSN Print: 2705-201x ISSN online: 2705-2001.
Ifamuyiwa, A.S. & Lawani, O. (2009). Interaction
patterns in Mathematics classroom in Ogun State.
Journal of Education, 6(3),35-56
Kalu, I. (2008) .Classroom interaction patterns, teachers‟
and students characteristics and student learning
outcome in physics. Journal of Social Sciences,
3(1),57-60.
Kouicem, K.(2012). The effect of classroom interaction on
developing the learner speaking skills. Journal of
Classroom Interaction, 39 (2), 1-27.
Maduewesi, B.U & Ezeani, L.U. (2012).Curriculum
implementation and instruction. Onitsha: West and
Solomon Publishing co. Ltd.
Offiah,F.C. & Akusoba , E.U. (2009). Effectiveness of
metacognitive learning Cycle to science instruction
for secondary school chemistry students. Journal of
Science, Technology and Mathematics,1(1), 23-30.
Onwioduokit, F.A & Oranu, P.C.(2012). Relative
effectiveness and classroom interaction technique in
senior secondary students‟ silence and confusion in
government classroom in Port Harcourt metropolis.
Mediterranean Journal of Social Sciences, 2(3),5170
Sahlbery, P. (2010). Interaction Analysis category
systems. Journal of Education. Retrieved from Pasi
sahbery.com.
Zaheed, B. &Moenikia, M.(2010). Study of teacherstudent interaction in teaching process and its
relation with students‟ achievement. Medwel
Journal of Social Sciences, 1(1)55-59.
56
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