<p>The purpose of this study was to analyze texts from four English textbook series for Swedish school years 7-9 as regards their readability and to investigate whether the text difficulty progresses within series with grade level and with each assigned difficulty level. The study also wished to make comparisons between these textbook series to determine if they are equivalent as regards their average readability level. The readability formulas Flesch Reading Ease and Flesch-Kincaid in Microsoft Word 2007 was used for calculation of the readability grade levels of a selection of 231 texts from the series <em>Good Stuff</em>, <em>Happy</em>, <em>Time </em>and <em>Wings. </em>The results from both formulas indicated that the texts in general become more difficult for each school year and with assigned level. However, the study showed that there are differences among the four series as regards their average difficulty levels and that there is a great difficulty range among texts.</p>

The purpose of this study was to analyze texts from four English textbook series for Swedish school years 7-9 as regards their readability and to investigate whether the text difficulty progresses within series with grade level and with each assigned difficulty level. The study also wished to make comparisons between these textbook series to determine if they are equivalent as regards their average readability level. The readability formulas Flesch Reading Ease and Flesch-Kincaid in Microsoft Word 2007 was used for calculation of the readability grade levels of a selection of 231 texts from the series Good Stuff, Happy, Time and Wings. The results from both formulas indicated that the texts in general become more difficult for each school year and with assigned level. However, the study showed that there are differences among the four series as regards their average difficulty levels and that there is a great difficulty range among texts.