Development and validation of a readability formula for Physics instructional materials

The study develops and validates a readability formula for physics instructional materials. It also determines the factors of readability for physics instructional materials.In developing the formula, 30 reading passages of no less than 100 words each were selected from 18 different books used in Philippine schools. These books were used in the elementary, secondary and collegiate levels.The passages were assigned a readability level by teachers engaged in education for at least 9 years. The readability level scale was from 4 to 16, representing the primary grades (Level 4) up to advanced or graduate level (Level 16). Twelve (12) variables were measured based on the textual and graphical characteristics of the passages.Factor analysis, using principal component analysis and varimax rotation, converged the variables into three factors. The factor names and the variables under each factor were:Factor 1 (Quantitative Relationship and Sentence Structure): Presence/absence of mathematical equation (MEQ), percentage of mathematical words (PMW), percentage of words associated to physics (PWAP) and average sentence length (ASL) Factor 2 (Technical Vocabulary): Percentage of derived concept words (PDCW), percentage of words specific to physics (PWSP), average word length (AWL) and presence/absence of graphics elements (GRA) andFactor 3 (Affective Score): Percentage of PEP words (PPEPW) and percentage of PEP sentences (PPEPS). Multiple regression analysis using readability level as criterion resulted into three equally plausible readability formulas. Comparative analysis of the three formulas\u27 proportion of explained variance, residuals, scatterplots and outliers led to the selection of the best model. This was called the JB Formula and is stated as:RDS = 5.5516 + 0.0949 ASL + 0.0951 PMW + .0506PWSPwhere: RDS = Reading Difficulty Score ASL = Average Sentence Length PMW = Proportion of Mathematical Words PWSP = Proportion of Words Specific to PhysicsThe JB Formula was validated against (a) other formulas, (b) reader judgment, and (c) reading comprehension scores. The developed formula was found valid as indicated by its significant relationship with the Flesch and the communication index formulas, and reading comprehension scores