The study sought to investigate the readability and content adequacy of the five recommended Physics textbooks used for teaching and learning Physics in Anambra State Secondary Schools.  The five recommended Physics textbooks were, Principles of Physics by Nelkon (Book A); New Secondary Physics for Senior Secondary Schools by Anyakoha (Book B); Senior Secondary School Physis by Ndupu, Okeke and Ladipo (Book C); Senior Secondary Physics by Okeke and Anyakoha (Book D) and Comprehensive Certificate Physics by Olumuyiwa, Awe and Okunola (Book E).  The study was guided by four research questions and three null hypotheses tested at 0.05 level of significance.  Literature was reviewed to elucidate the variables under theoretical framework, conceptual framework and then empirical studies. The evaluation research design was adopted.  The design for the study was evaluation. There were two sets of population for the study, namely, Physics students and Physics teachers. Twenty two thousand, two hundred and seventy one (22, 271) Senior Secondary School Physics Students and 119 Physics teachers in 105 Senior Secondary Schools in the 5 education zones in Anambra State. Out of the 105 Senior Secondary Schools, 10 Senior Secondary Schools were drawn from Bach of the 5 education zones. Ultimately three thousand, eight hundred and sixty one (3,861) Physics Students and 13 Physics teachers in the 10 Secondary Schools were involved in the study. Data were collected through cloze tests for determining readability. Quantitative Approach to Content Evaluation of Science Textbooks (QACEST) was used to quantitatively measure the content validity of the five criteria of Index of Topical Coverage (ITC), Learning Activity Index (LAI), Study Questions Index (SQI), Illustrations Index (ILI) and Chapter Summaries Index (CSI) for each of the five Secondary School Physics text evaluated in this study. The cloze test instruments were face validated. The reliability coefficients for the cloze test instrument were found to be 0.75, 0. 86 and 0.87 for Book A, 0.75, 0.97 and 0.88 for book B; 0.89, 0.77, and 0.81 for book C; 0.87, 0.81 and 0.85 for book D while 0.87, 0.89 and 0.86 was for book E for SSI, SSII and SSIII respectively, using Pearson’s Product Moment Correlation Coefficient. Also equivalence test coefficient for the cloze test instrument were found to be 0.89, 0.82 and 0.79 for the three respective classes using Pearson’s Product Moment Correlation Coefficient. Research question 1 was answered using percentages. Research questions 2 and 4 were answered using mean content rating scores. Research question 3 was answered using mean readability score.  The hypotheses were tested using analysis of variance (ANOVA) at 0.05 level of significance.   The results revealed that Book B was the had in the highest readability percentage score of 54.85% followed by Book C, (39.47%); Book E, (38.84%); Book A (38.00%) and Book D (37.96%).  Book B also had the highest overall mean content rating score of 0. 52 on the 5 content rating indicators, followed by Book E (0.49); Book D (0.48) Book A (0.47) and then Book C (0.42).   The mean readability scores of SSII students were highest across the four books A, C, D, E, except for book B where the mean readability score was highest for SSI. Thus, Book B, for SSll, had the best readability value. Considering the influence of class level on content rating indicators; SSIII topics scored the highest (0.67) on ITC, followed by SSII (0.59) and SSI (0.55).  On LAI, SSIII scored the highest (0.83), followed by SSII (0.82) and SSI (0.74).  On SQI, SSII topics scored the highest (0.64), followed by SSIII (0.61) and SSI (0.52).  On ILI, SSIII topics scored the highest (0.38), followed by SSII (0.30) and SSI (0.25).  On CSI, SSII scored the highest (0.33), followed by SSI (0.28) and SSIII (0.27).  A post hoc test for hypotheses indicated that book B (New School Physics for Senior Secondary Schools by Anyakoha) was most readable while the curriculum for SS11 was mostly covered for each of the books, A, B, C, D and E. Considering the content reflected in each of the five physics books evaluated in this study, vis-à-vis the Senior Secondary School Physics curriculum used in Nigeria, Textbook B New School Physics for Senior Secondary Schools by Anyakoha was found to be the best content-wise.




Background of the Study

With the current high level of global technological awareness and emphasis on science education, there is a renewed call by science educators in Nigeria, for a functional Physics education in Nigeria Ale (2003).  This call is based on the desire for an educational system capable of promoting industrial development, in many countries of the world, including Nigeria.  For instance, the Federal Government of Nigeria launched the senior secondary school Physics curriculum in 1982 in response to this desire, according to Ale (2003).  The objectives of the senior secondary school Physics curriculum clearly reflect the need for physics to provide the basis for Nigeria’s functional physics. The objectives of this curriculum are:

  1. Facilitate a transition for scientific concepts and techniques acquired in Integrated Science with Physics;
  2. Provide students with basic knowledge in Physics concepts and principles through efficient selection of content and sequencing;
  3. Show Physics in its inter-relationship with other subjects;
  4. Show Physics and its link with industry, every day life, benefits and hazards; and
  5. Provide a course, which is complete for pupils not proceeding to higher education, while it is at the same time a reasonable adequate foundation for a post secondary Physics course.

One can argue that these objectives are not fully achieved since students

achievement in physics public examinations like the West African Examination Council and National Examination Council are poor as shown in Appendix 1. Most candidates who sit for these examinations fail in both WAEC and NECO.

To achieve these objectives, the curriculum in Physics is expected to reflect contents and methods, which will provide relevant and useful knowledge and skills useful for technological and industrial development. This implies that Physics curriculum review is expected to take care of the challenges of the modern world.  Since much of the knowledge and skills in Physics which students are expected to acquire are reposited in Physics textbooks, it is important that such books have adequate content coverage and are readily readable by students such books are meant for.  This explains why the Secondary Physics textbooks used for Physics teaching is of major concern to the researcher especially as it concerns the determination of the readability and content validity of secondary school texts used for teaching Physics. No matter how well designed a curriculum is, it cannot be effectively implemented without instructional materials.  According to Onyejemezi (1989), instructional materials play vital roles in implementation of the curriculum.  That is, the instructional materials equip the teachers with relevant knowledge and strategies while providing the learners with easy link between instructions and practice.

Onyejemezi (1989) identified various types of instructional materials, which range from models, print materials to audiovisuals.  Among the various resources in teaching sciences, textbooks are identified as the most indispensable and readily available to both the teachers and the students (Nworgu, 1991 and Kelly, 1997).  In the teaching and learning of any subject both teachers and students rely on text materials and as such it is not doubtful then that the quality of textbooks in use will determine, to a large extent the quality of learning and transfer of such learning which will occur (Nworgu, 1991).  Hence the quality of educational materials such as textbooks is most fundamental where information presented is reliable, valid and authoritative.  Similarly, the appropriateness of the vocabulary and the presentation of concepts appropriate to the level of the learner, problem – solving,, the learner’s clarity of objectives, methods and procedures are also very indispensable qualities that characterize good educational materials such as textbooks (Ali, 1996).   Also, other important qualities of textbooks are the number and qualities of student’s and teacher’s activities, provision of information for obtaining related resources, inclusion of assessment criteria and the inclusion of information on how to establish the extent the learner has attained each of the learning indicators (Ali, 1996).  This implies that active engagement of the learners through activities that are challenging, interesting and appealing may lead to motivation and subsequent development of good study habits.

Kelly (1997) maintained that the quality of textbooks pertains principally to its contents and its readability.  From the content perspective, it embodies the main substance or learning experiences, which the learner is expected to acquire.  Ali (1999) regarded content of a textbook as the facts, ideas, theories, and principles of a given subject matter of instruction, which are expected to be firstly,  in complete harmony among themselves and ultimately in harmony between other related subjects (that is, harmony in terms of the interdisciplinary content).  Besides the quality of print, another characteristic of a content is the style of presentation of facts, ideas etc such that the teacher can use the book to communicate knowledge to the learner as well as allow the student to learn the content on its own using the textbook. Also, content of a textbook has been defined by Igbeyi (2001) as the totality of topics presented in a textbook, in a given discipline.  Such contents must be appropriate, adequate, and logically well presented in such a way that the learner could benefit from reading the contents.  When this does not happen, the content of the textbook is said to be confusing, haphazard and may create misconceptions to the reader.

The content of the textbook according to Nworgu (1988) is viewed in terms of its topic coverage, learning activities, review questions, illustrations and chapter summaries.  Based on the above descriptions of the content of a textbook, presented in the previous paragraphs by Nworgu (1988), Kelly (1997), and Ali (1996 and 1999) one can consider the content of a textbook to mainly concern the issues of index of topical coverage, chapter summaries index, illustration index, study questions index and learning activity index contained in the book, all of which can be evaluated. Index of tropical coverage means, the extent the textbook covered the contents prescribed in the curriculum.  Chapter summary, according to Nworgu (1996), is the extent to which the summaries promote a more permanent overview or understanding of the content of the text.  Illustration refers to how the use of figures, charts, diagrams, tables, pictograms, graphs etc contained in the textbooks allow for better understanding of the contents of the book.  Study questions relate to the content questions in the text encourage the learner to be creative, ask and seek answers to top demanding questions.  Learning activity concerns the extent to which the contents of the textbooks’ activities encourage optimal participation by the students on the contents of the book.  Contents of a textbook can also include its practiced orientation, worked examples of quantitative problems, accuracy of content, clarity of language but these were beyond the scope of the present work. Readability refers to the inherent difficulty or easiness of the sentence or passage to reading with understanding.  In other words, readability is the sum total of all the factors that affect the success of a reader during the process of reading.   According to Etim and Umoh, (1983), readability can be regarded as the quality of a written message which makes it possible to understand its meaning. The indicator that constitute readability are the overview of each concept specified, presentation of facts and ideas, legibility of diagrams, illustrations and sketches, typing and spacing of words, printing errors, communication. But these are outside the scope of the present study.

The above explanations of readability indicate that there are two sides to the reading process, namely – the text and the reader.  Therefore readability is concerned with how well the reader understands the text he has read.  In other words, readability is the determination of the contents of a textbook which a person has read and the extent understood by him. This definition of readability is in consonance with Taylor’s (1996) opinion that readability and comprehension go hand in hand.  In the same vein, other researchers argue that if a passage is readable, means that it is understandable, then the scores that measure readability should also measure comprehension (Herber, 1992 and Gibson, 1996).  The ability to read and understand its content i.e. its readability, is important to the learner. The interest the reader has on a book also enhances readability. Indeed, the Nigerian National Council on Education as reported by Eya (2001), stipulated that the State Ministry of Education should periodically review standard textbooks used in teaching in secondary schools every three years to ensure that books are readable by students.  A number of new secondary school Physics textbooks have been produced and introduced into the secondary school educational system in Nigeria, in the last twenty years or so, often, in response to new curriculum changes.  Also, some of the existing old editions of Physics textbooks have been reviewed to relate them to the current needs of the curricula and the examination bodies. The readability of each of these textbooks need to be determined, especially since it is the case that the approval of textbooks for schools has also experienced a number of problems.  One of such problems is that of approval of textbooks for use in schools without subjecting them to due processes of evaluation.  Considering also the level of academic exposure of the approving committee and procedures for approval of textbooks it may be the case that the content and readability status of some of the recommended texts are obviously in doubt (Nworgu and Harbour-Ibeaja, 1985; Brandy and Scoll 2001).  Also the current poor achievement in Physics SSCE results as shown in Appendix I have raised some doubts on the suitability of recommended text materials in Physics. For instance, looking at Appendix I, it can be seen that the highest percentage pass (A1-C6) was 31.1% in 1988 while the lowest percentage of pass was 6.3% in 2001. The percentage of passes for other years is shown in the same appendix, for instance in 2004 percentage of pass was 7.3% while in 2005 it was 7.5%.  Therefore, since learning and transfer of learning depend to a large extent on the content and readability of text materials, a regular evaluation of recommended textbooks for schools ought to be carried out by doctoral student researchers and science teacher educators; among others.  When such regular evaluation of recommended textbooks is not done, it is difficult to claim that recommended textbooks have acceptable content coverage and readability indicators.  For some teachers, the poor quality of Physics texts, in terms of their contents and readability may contribute to students low and unimpressive achievements in Physics by students. It is also likely that the learners level of achievement (the high average and low achievers) affect their readability but this should not be equated with their comprehension of the passages in a book they read.

Based on the criteria stated above, one can conclude that they all have the appropriateness of texts to level of the class in mind.  This is in line with the views of Nworgu and Harbor-Ibeaja (1985) that any set of criteria for evaluating texts should be learner– centered.  It is therefore right to say that any Physics text should be constructed in such a way as to take care of the different arms of the classes.  Smith (1981) supported this fact by saying that there are stages in acquisition of phrases, word associations and language skills ability.

However with regard to the level of  class of the student as a readability factor, literature shows that a number of research studies have focused on the factor of different students’ class ability levels in the readability of secondary school Physics textbooks.  For instance, Ukabul (2003) found that reading and comprehension abilities of British secondary school Physics students generally varied according to their grade levels, in favour of more senior students.  Ukabul (2003) also found that there was a general tendency for the prescribed Physics texts to reflect increasing complexity in the required reading and comprehension abilities from lower grade level to higher-grade levels.  A study similar to that of Ukabul (2003) was carried out by Ombima (2004) with two prescribed senior secondary textbooks used for Physics teaching in Kenya.  Each of the evaluated Physics textbook was in a 3-level series.  Ombima (2004) concluded that none of the books showed evidence of reflecting the readability and content levels of the books the physics students were meant for.  Thus, there is need to investigate these two issues indicated above in the context of physics to find out the status of Physics textbooks, for SSI, SSII and SSIII classes, in meeting the unique reading ability and comprehension of Physics students such textbooks were meant for.

Since readability has been identified as an important criterion under which a text can be evaluated, a lot of tests for measuring readability are available.  Such tests include Dale and Chall test, Flesch test and Spache test.  Also is the cloze procedure which was developed by Taylor (1953, 1986).   Cloze procedure according Taylor (1953, 1986) is a method of intercepting a message from a writer, mutilating its language by deleting its language patterns or parts and so administering it to readers that their attempts to make the patterns whole again potentially yield a considerable number of cloze units.  The choice of cloze technique was preferred in the present study because it is considered more sensitive and comprehensive compared to other technique according to Taylor (1986).  The researcher however adopted cloze technique with some slight modification to suit the nature of the present work.  Thus, the researcher did not delete the nth word in the passages used in this study because it may be the case that such a word had no critical meaning in the passage concerned.

Fully aware of other major factors affecting secondary student’s achievements in physics, such as quality of teaching (Chim, 2004); poor mathematical skills needed in physics (Ali, 1988); poor laboratory facilities (Lassa, 2005) and gender (Ivowi, 2002) one is aware that there is scanty research on secondary school readability and content that there is scanty research on secondary school readability and content evaluation of physics text books in Nigeria.

Against the background of scanty research evidence in the readability and content evaluation of senior secondary school Physics textbooks in Nigeria, there is the need for obtaining empirical data on this issue especially since there are no evidences of such evaluation based on secondary school Physics textbooks.  Therefore, this study will address this need especially as it concerns obtaining empirical data on the five recommended secondary school Physics textbooks, on the variables of topical coverage, chapter summaries, study questions, learning activity and illustrations. The present practice of selecting and recommending Physics textbooks for secondary schools requires the state government to set up a panel of subject experts (Physics teachers), ministry officials and other stakeholders who will do the selection or book review.  The panel is expected to sit and compares the available textbooks based on some agreed criteria such as cost of books, quality of print, content coverage and interdisciplinary considerations among others.  It is expected that the overall performance of each of the reviewed books would lead to the selection of the best book, in all.


Statement of the Problem

Students’ results in senior secondary school Physics examinations have been very poor (WAEC, 2003). This situation coupled with students’ poor attitude towards Physics and low enrolment in Physics tend to raise doubts as to the possibility of realizing the objectives of Physics education in secondary schools.

Since text materials are the major resources available to students in Physics and considering the fact that instructional resources are known to boost interest and achievement of students in sciences, it has been suggested by some researchers such as Ali (1996) and Okoh (2002) that Physics textbooks be evaluated periodically.  Unfortunately, in Anambra State secondary schools, a number of textbooks have been recommended for teaching Physics without subjecting them to due processes of textbook evaluation relative to their content adequacy and readability (Akuezuilo 2005).

Textbook evaluation is considered important as it affects the relevance, usefulness and coverage of a particular textbook vis-à-vis its stated curriculum objectives. The issue of Students’ class levels (SSI, SSII, SSIII) being capable of influencing their ability to read the recommended Physics Textbooks, needs to be investigated. The expectation of physics students, their teachers and governments in Nigeria, is that if the textbook has satisfactory content rating and readability values, the use of such a book is expected to enable students read and understand the topics and consequently achieve higher results in the study of Physics. In the light of the above, the study is faced with the problem of evaluating the recommended Physics textbooks in the secondary schools relative to their content, proper arrangement of ideas required and readability.


Purpose of the study

The purpose of this study is to evaluate the readability and content of Physics textbooks in use in Anambra State senior secondary schools. Specifically, this study intends to

  1. Determine the readability scores of each of the five recommended Physics textbooks in use in Anambra State Senior Secondary Schools.
  2. Determine the adequacy of each of the five recommended Physics textbooks in terms of the topical coverage, chapter summaries, study questions, learning activities and illustrations.
  3. Assess the influence of class level on the readability of each of the five recommended Physics textbooks, based on the SS1, SS11, and SS111 readability scores.
  4. Assess the influence of class level (i.e. SS1, SS11, and SS111) on the topical coverage, chapter summaries, study questions, learning activity and illustration in each of the five recommended textbooks in use in Anambra State Senior Secondary Schools.

Significance of the Study

The findings of this study will have a number of theoretical and practical significances.  The study is considered theoretically significant because the findings will add to existing theoretical knowledge in the area of readability and content evaluation of the prescribed Physics textbooks.

One of the practical significances of the study is that the publishers of five respective Physics textbooks evaluated will be sent the findings of the study, as they concern the use of illustration, topical coverage, study question, chapter summaries and learning activities for improving the quality of secondary school Physics textbooks they publish in their subsequent edition.  It is expected that they will become interested in finding solutions to the deficits found in their books and correct the deficits.

The study is considered significant because it will provide data for determining the suitability of the recommended textbooks in terms of their relative readability. It is expected to benefit physics students by way of aiding them select books, which they can read and understand, and so be able to do better in physics (examinations). Similarly physics teachers would be able to select better physics textbooks for use in teaching their students, on the basis of the findings of the study.  The researcher will provide results of the study to Ministry of Education, Anambra State, the senior secondary school authority, students and parents on the right quality of Physics textbooks to choose for Physics students.  Thus invariably the study will reveal the textbooks that are more readable and recommend them for students.  The choice of high quality Physics textbooks for students will go a long way to boost the interest of students in Physics with its far reaching effects on their achievement and enrolment in Physics.  Such information will be communicated to the Ministry of Education and stakeholders for use in guiding it in selecting textbooks for Physics in their secondary schools.

This is considered empirically significant because subsequent researchers interested in investigating the content and readability of secondary school science textbooks can locate the present work in the library and understanding the methodology and findings of the present study, so as to improve their proposed methodology based on present work.  So to that extent, the present study is considered empirically significant to other forthcoming researchers, interested in carrying out studies similar to the present work.


Scope of the Study

The study was restricted to five Physics textbooks recommended for teaching Senior Secondary Schools in Anambra State. The five textbooks which are those recommended by the Ministry of Education, Anambra State, in September 2000.

  1. Principles of Physics by M. Nelkon (Published by Chatto and

Windus  Ltd. New Edition, 1999)

  1. New School Physics for Senior Secondary Schools, (SS1 – SS3), by
  2. W. Anyakoha (Published by Africana Publishers Ltd. Nigeria, 2006).
  • Senior Secondary Physics (Books 1-3) by B.L.N Ndupu; P. N.

Okeke; O.A. Ladipo (Published by Longman Nigeria PLC, 1999).

  1. Senior Secondary Physics (SS1 – SS3) by P.N Okeke and M.W.

Anyakoha (Published by Macmillan Education Ltd., London, 2002)

  1. Comprehensive Certificate Physics (SS1-SS3), by Olumuyiwa

Awe, O.Okunola (Published by University Press PLC., Ibadan, Nigeria, 2004).


The five Physics textbooks were chosen because they were the most commonly available and used Physics texts for teaching Physics in Anambra State senior secondary schools.  The readability for the contents of SS1, SS11, and SS111were compared, respectively across the five recommended books evaluated in this study. This was intended to obtain empirical data for comparing the readability of the five recommended physics books, on the basis of class level.


Research Questions

The following research questions guided this study:

  1. What is the readability score of each of the five recommended Physics textbooks for teaching SSI, SSII and SSIII Senior Secondary Schools respectively in Anambra State?
  2. What is the mean content rating score of each of the five recommended textbooks for teaching Physics in Anambra State Senior Secondary Schools as measured by Index of Topical Coverage (ITC), Learning Activity Index (LAI), Study Question Index (SQI), Illustration Index (ILI) and Chapter Summaries Index (CSI)?
  3. What is the influence of SSI, SSII and SSIII class levels on the mean readability score of the five recommended Physics textbooks?
  4. What are the mean content rating scores of SSI, SSII and SSII recommended physics text books evaluated in this study with regard to the topical coverage, learning activities, study questions, illustrations, and chapter summaries?



The following null hypotheses tested at the 5% level of significance, guided the study:

HOI:               The mean readability score of the Physics textbooks for teaching senior secondary Schools in Anambra State will not differ significantly among the five recommended Physics textbooks.

HO2:               The Content rating score of the Physics textbooks for teaching senior secondary schools in Anambra State will not differ significantly among the five recommended textbooks as measured by Index of Topical Coverage (ITC), Learning Activity Index (LAI), Study Question Index (SQI), Illustration Index (ILI) and Chapter Summaries Index (CSI).

HO3:               The mean readability scores of the five recommended Physics textbook for teaching Senior Secondary Schools in Anambra State will not differ significantly among SSI, SSII and SSIII class work covered in the five textbooks.


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