Matching reading materials to learners with the appropriate level of proficiency has been the focus of attention for many scholars. To this end, readability formulas have been developed. Despite being efficient and user friendly, the formulas have not been able to stand to the test of research, thus undergoing some criticism on the grounds that they are not sensitive to the modification in the factors they are based on. Furthermore, they fail to consider other factors which play roles in the comprehension of written materials. Some scholars, based on such criticisms, have noticed the absence of some factors in readability formulas. Some of these factors are cultural origin, structure of theme and core/non-core words, and conjunctions. The present study constitutes an attempt to investigate the relationship between readability of written materials and the learners’ performance at two proficiency levels of intermediate and advanced, the relationship between cohesion markers (grammatical markers, conjunctions and lexical markers) and the readability of written materials, and also the relationship between these cohesion markers and the performance of learners of English as a foreign language at the two aforementioned proficiency levels. To calculate the readability of the material, two prominent readability formulas, Flesch and Fog Index, were employed. The results indicated a significant correlation between the readability of passages and the learners’ performance at both levels. Only grammatical cohesion markers were shown to be significantly correlated with the readability of the written materials. The learners’ performance correlated significantly with grammatical cohesion markers at intermediate level and with lexical cohesion markers at advanced level

Scientific language has always been both a source of difficulty for the students of science and, in the recent decades in particular, a theme for speculation for the scholars seeking to describe and analyse language as it is used and conceived. The language of science has always been presumed to be more difficult than the language used in other fields. Scientific concepts and their sophistication are one source of its difficulty. The writing style and dynamics preferred by writers in the fields of science is commonly considered another source of such difficulty. Nominalisation, the use of derivative nouns of verbs and adjectives, which is more prevalent in the language of science compared with the language used elsewhere, is another feature attested to by many scholars. The present study aimed at comparative investigation of the phenomenon of deverbal nominalisations (nominalisations with verb origin) across written and spoken scientific language. The spoken samples were chosen from BBC’s programs in the genre of science and the written samples from science textbooks and credited science magazines (different issues). The samples in each modality included 400,000 words (for each modality) amounting to 800,000 words as the total size of the corpora considered. The findings showed a higher frequency of verbs in spoken modality and of nominalisations in written. Another interesting point was the highest frequency of material process type in both verbs and deverbal nominalisations. (The typology of processes from the Hallidayean systemic functional grammar framework was the basis for classification of verbs and their respective nominalised editions.) Relational process type which claimed the second highest frequency among verbs showed a much lower frequency among nominalisations. The consideration of the slots accommodating the nominalisations in the sentences also revealed insightful points about possible differences between spoken and written language (of science) in terms of the concentration of semantic and lexical density