Development and Validation of an Instrument for Assessing Students’ Practical Skills in Joinery at Science and Technical College Level in Nigeria

The fact that a student can present a quality product does not constitute a positive proof that process practical skills are obtained. This study was therefore designed to develop and validate an instrument for assessing students’ practical skills in joinery at technical college level. Four research questions were set to guide the study and a null hypothesis. The study adopted the instrumentation design and was carried out in Adamawa State. The population for the study was sixty four (64) respondents. The instrument was subjected to validation, reliability test and results obtained from task-by-task reliability coefficient range from 0.67 to 0.98 through Cronbach Alpha coefficient. The instrument was imperiled to factor is alanalys is where a practical skill item was discarded. Based on the findings; nine (9) tasks with corresponding eighty three (83) practical skills were developed. The study recommended that (i) efforts should adopted to enforce the use of Joinery Skill Assessment Instrument (JSAI) for assessing students’ practical skills in Nigerian technical colleges. (ii) Teachers should be encouraged to study and acquaint themselves with the use of JSAI. (iii) Stakeholders (ministries and institutions) should endeavor develop platforms (conferences, workshops) where the use of this new assessment instrument can be encouraged. www.scholink.org/ojs/index.php/wjer World Journal of Educational Research Vol. 7, No. 4, 2020 10 Published by SCHOLINK INC.


Introduction
The National Policy on Education (FRN, 2013) spelt out the goals of TVET as follows: to provide trained manpower in the applied sciences, technology and business particularly at craft, advanced craft and technical levels; to provide the technical knowledge and vocational skills necessary for agricultural, commercial and economic development and to give training and impart necessary skills to individuals who shall be self-reliant economically. The purpose and goals of TVET cannot be realized without a sound, reliable and implementable and assessment of the curriculum content achieved by learners. The National Board for Technical Education (NBTE) developed a modular curricula for all the trades offered at science and technical college level. The curriculum was broken into modules of employable skills, which the students are expected to master within a given time frame (Tika, 2015). The breakdown of the curriculum into objectives also provides a level ground for assessment process to determine the overall achievement of the curriculum objectives and goals. Assessment is a form of evaluation that uses collected data for estimating the work, quality or effectiveness of a programmer project. Technical education assessment is the process of calculating or measuring the extent of skills the students have acquired. Assessment could be of an individual learner, class, workshop, the school or the educational system as a whole. In this study, assessment refers to a process of determining the performance of a student's skills by asking the student to perform tasks that require those skills.
Assessment is one of the most important aspects of teaching and learning process; because it propels student to learn. Ombugus (2013) defined assessment as the process of collecting evidence and making judgment on the extent and measuring progress towards the performance requirements set out in a standard learning outcome. Skills according to Ogbuanya (2010) are the abilities in carrying out a task. Tika (2015) defined task as logically related set of actions required for completion of a job objective.
In the context of this study, task referred to a piece of work that must be performed on the work piece or industrial project in order for it to be successful. The carpentry and joinery trade curriculum emphasized tasks and skills that students are expected to acquire in wood preparation, joinery, formwork, framing carpentry and joinery machining, hand tools fitting and finishes among other operations (Umar, 2014). Each of these operations have tasks that are performed through a sequence of practical activities or skills in consonance with the objectives. The carpentry and joinery trade teachers have to improve on the joints used in frame-like construction where the wood members are jointed end to edge, with their edges at right angles, e.g., paralleled doors, tables, chairs, picture frames among others. The face sides of the wood members are usually flush. Some of the common joints for frame construction according to Umar (2014) are: halving go rhalf-lap, mitred, dowelled, mortise and tendon, bridle among other joints. The variations of these joints are occasionally necessary and may be designed to suit special jobs. Okwori, Adamu, and Odo (2013) concluded that the knowledge, skills and application of manipulative skills to various types of joints must be properly evaluated hence the need for joinery skill assessment instrument.
Based on the Item Response Theory propounded by Hambleton, Swaminathan, and Rogers (1991), which is a body of logically related statements describing the application of mathematical models to data from questionnaires and tests as a basis for measuring abilities, attitudes, skills or other variables.
The use of this theory as an approach to developing a valid instrument provide these important features; it provides information about the amount of manipulative skill measured by each task, student performance on a given task provides information about how much skillful each student is so far.
Supporting the profounder, Gall, Gall, and Borg (2007) describe edited responses theory as an approach to test construction. They also considered factor analysis to play a major role in the development of various types of assessment instruments used in education. For effective assessment, the joinery practical skills instrument should be valid.
Validity of an instrument, according to Nwabueze (2009) is the degree to which an instrument measures what it is designed or made to measure. An instrument with high validity will measure accurately the particular qualities it is supposed to measure. In the views of Okwelle and Okoye (2012), validity of a measuring instrument is the property of a measure that helps to ensure that the instrument measures what it supposed to measure. Enyi (2009) classified four types of validity, face (logical), content (domain), construct and criterion-referenced (concurrent and predictive) validity. Face, content and construct validity were utilized in this study. In the construct validity, factor analysis is employed to determine the validity of an instrument. Ombugus (2013) observed that the higher the absence of low factor loading skill items, the more important and suitable the instrument items. An instrument used for assessing students should not only bevalidbut also reliable.
Reliability of a measuring instrument according to Ofuebeand Izueke (2011) is the ability of the instrument to measure consistently the phenomenon it is designed to measure. It therefore means the consistency with which an instrument measures what ever it measures. The use of valid and reliable practical skill test for assessing NTC students in carpentry and joinery trade will provide an effective tool for evaluating both process and product skills acquired by the students on carrying out tasks.
However, at present only product assessment is employed at the science and technical colleges. The product rating method used by the teachers and examination bodies in measuring performance of the students is in adequate. The current practice has made it impossible for the full achievement of the objectives of carpentry and joinery trade in science and technical colleges. This is because procedural steps to arrive at the completed project are not properly assessed. The study is therefore prompted on the derisory nature of the present method of evaluation which is product-based, there is an urgent need to improve overhaul the standard of assessment in carpentry and joinery trade by using valid and reliable assessment instruments which will take account of the processes of practical activities leading to the completion of the final practical products. The assessments of practical skills practiced by the carpentry and joinery teachers and final examination by NABTEB have produced graduates of carpentry and joinery that are unemployable in the field. This explains why many of the graduates are into other unskilled jobs like commercial motorcyclist, motor-parks workers others even hungry, kidnapping among others or remain unemployed. This study was therefore designed to develop and validate an instrument for assessing students' practical skills in joinery at science and technical college level.

Method
The study adopted the instrumentation design and was carried out in Adamawa State. The population for the study is sixty four (64) respondents. Purposive sampling technique was employed to arrive at the use of Government Science and Technical College, Yola for the trial test and the entire population was used as sample size since it is manageable. The Joinery Skill Assessment Instrument (JSAI) was developed using the following strategy build up based on the suggestions of Okwelle and Okoye (2012) and UNESCO (2002).   incorporated into the instrument. The instrument was subjected to factorial analysis where a practical skill items was discarded from the six NTC Joinery modules. Three teachers of Carpentry and Joinery were used as assessors for observing and assessing the students as they execute given tasks with corresponding skills of the developed instrument during the try-out. Cohen, Manion and Marrison (2011) recommended that a coefficient rangingfrom0.51to1.00indicate high degree of agreement between two or more assessors. The method of data analysis includes the factorial analysis, Simpson's (1972) taxonomy of psychomotor objectives, Cronbach Alpha coefficient, Kendall coefficient of concordance (Tau) and z-Test.

Purpose of the Study
The main purpose of this study was to develop and validate an instrument for assessing students' practical skills in joinery at science and technical college level. Specifically, the study will: -1) identify the practical task items considered appropriate for inclusion in Joinery Skill Assessment Instrument (JSAI) for assessing students' practical skills in science and technical colleges, 2) identify the practical skill items considered appropriate for inclusion in Joinery Skill Assessment Instrument (JSAI) for assessing students' practical skills in science and technical colleges, 3) determine the validity of the developed instrument for assessing joinery trade students' practical skills in science and technical colleges, 4) establish the reliability of the developed instrument for assessing joinery trade students' practical skills in science and technical colleges.

Hypothesis
One null hypothesis was tested at 0.05 level of significance: Ho 1 : There is no significant difference between the mean responses of carpentry and joinery craft teachers and carpentry and joinery professionals on the practical task items considered appropriate for inclusion in Joinery Skill Assessment Instrument.

Results
Research question 1. What are the practical task items considered appropriate for inclusion in Joinery Skill Assessment Instrument (JSAI) for assessing students' practical skills in science and technical colleges? The result of factor analysis from the data obtained shows that nine (9) practical tasks from the psychomotor modules of Joinery curriculum at the science and technical colleges are appropriate. With a cluster factor loading ranging from 0.500 to 1.000, it can therefore, be concluded that the practical tasks obtained through content analysis of the NBTE Joinery curriculum were unanimously accepted by the respondents.
Research question 2. What are the practical skill items considered appropriate for inclusion in Joinery Skills Assessment Instrument (JSAI) for assessing students' practical skills in science and technical colleges? taxonomy of psychomotor objectives. This followed a process of task analysis (3) generating practical skill items which closely fit the table of specification. The skill items were subjected to factor analysis using 0.50 as factor loading at 5% over lapping variance. Therefore, any practical skill with factor loading of 0.50 and above was included in the Joinery Skill Assessment Instrument while skill items with factor loading less than 0.50 were not included in the final copy of JSAI. One (1)  Research question 3. What is the validity of the developed instrument for assessing carpentry and joinery trade students' practical skills in science and technical colleges?
The instrument was subjected to face, content and criterion-referenced validation as well as factor analysis.   revealed that none of the tasks and corresponding skills in the instrument has reliability coefficients of less than 0.6. This shows that the entire tasks can be included in the instrument. In order to establish the inter-rater reliability in the instrument, atria ltesting was conducted using 15 NTC III students of Joinery and three teachers (assessors). Data obtained from the trial testing was analy seducing Kendall's Coefficient of Concordance, Tau (W) to find out if there is significant relationship between the three rater's scorings in the developed instrument for assessment. The degree of agreement of concordance among the raters on the instrument scorings were then computed. The inter rater reliability of the 3 raters were found to be 0.64, 0.85 and 0.71 for raters A and B; Band C; A and Respectively. These values were in agreement with the recommendation by Cohen et al. (2011) that a coefficient ranging from 0.51 to 1.00 indicate high degree of agreement between 2 or more examiners.
Ho 1 : There is no significant difference between the mean responses of Carpentry and Joinery teachers and Carpentry and Joinery professionals on the practical task items considered appropriate for inclusion in Carpentry and Joinery Skill Assessment Instrument. The results of z-Test on Table 4  implies that there is no significant difference between the mean responses of carpentry and joinery craft teachers and carpentry and joinery professionals on the practical task items considered appropriate for inclusion in Joinery Skill Assessment Instrument.

Discussion
The findings relating to construct validity of the psychomotor modules revealed nine tasks considered appropriate for inclusion in the instrument. The first output from the factor analysis employed is the reliability statistics which ranges from 0.985 to 0.997 for all the tasks and corresponding practical skills hence appropriate for inclusion in the instrument. However, a practical skills could not load and was discarded. After the reliability statistics then the table of descriptive statistics for all the variables under investigation. This tables typically give the mean, standard deviation and number of respondents (N) who participated in the survey are given. Looking at the mean, one can conclude that checking the machine before operation and griping the blade by tightening are the most important variables that influence process skills. They had the highest mean of 13.82 and 14.11. The next item from the output is a table of communalities which shows how much of the variance. That is, the communality value which should be more than 0.5 to be considered for further analysis. Otherwise, these variables are to be removed from further steps of the factor analysis, if the variables have been accounted for by the extracted factors.
Total Variance Explained shows the actual factors that were extracted. In the section labeled "Rotation Sums of Squared Loadings," it shows only those factors that met the cut-off criterion (extraction method). In this case, there were two factors with eigen values greater than 1. SPSS always extracts as many factors initially as there are variables in the dataset, but the rest of these did not make the grade.
The "% of variance" column informs how much of the total variability (in all of the variables together) can be accounted for by each of these summary scales or factors. Factor 1 representing the tasks Gauging lightly round one end of each piece to receive dovetail/pins, chiseling off the waste portion halfway down each piece, and removing end piece by sawing across grain then mortising out centre piece received the highest factor loading of 1.00 probably because of the importance in process skills development. The results obtained from task-by-task reliability coefficient range from 0.67 to 0.99, while the overall reliability of the instrument is 0.88. Therefore, given the high reliability coefficients for various tasks in the instrument, the answer to the research question about the reliability of the tests was in the affirmative.

Conclusion
The major findings of the study serve as the basis for drawing conclusion that the developed instrument is a valid and reliable assessment instrument that could be used in assessing student's practical skills in Joinery in science and technical colleges in Nigeria. It is expected that Joinery teachers in technical colleges will be encouraged to use the instrument to assess students' practical skills in the trade. The school administrators and potential employers will also find the instrument useful as it will enable them to make proper placement of students for admission in to higher institution, also it will help to predict students' performance when admitted for further education as well as employment.
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Recommendations
Based on the findings of the study, the following recommendations were proffered: 1) The Ministry of Education should adopt and enforce the use of Joinery Skill Assessment Instrument (JSAI) for assessing students' practical skills in Nigerian technical colleges.
2) Technical colleges teachers of Carpentry and Joinery trade should be encouraged to study and acquaint themselves with the use of the new assessment instrument. Ensure proficiency in the use of equipment and machines, Ability to read and understand wood structure and texture Complete the project within as pacified time limit Blue print inter predation Ability to understand wood behavior in different conditions Safety and health considerations Ability to work as an individual  Vol. 7, No. 4, 2020 15 Apply glue to fasten the joint 16 Strengthen the joint with nails 47 Fit together then clean up.