In this article, we introduce HelexKids, an online written-word database for Greek-speaking children in primary education (Grades 1 to 6). The database is organized on a grade-by-grade basis, and on a cumulative basis by combining Grade 1 with Grades 2 to 6. It provides values for Zipf, frequency per million, dispersion, estimated word frequency per million, standard word frequency, contextual diversity, orthographic Levenshtein distance, and lemma frequency. These values are derived from 116 textbooks used in primary education in Greece and Cyprus, producing a total of 68,692 different word types. HelexKids was developed to assist researchers in studying language development, educators in selecting age-appropriate items for teaching, as well as writers and authors of educational books for Greek/Cypriot children. The database is open access and can be searched online at www.helexkids.org.

The concept of a linearly ordered dontent domain (LOCD) is discussed and applled to a spelling example. A logistic analysis of the occurrencc of first introduction of spelling words into the curriculum ii presented, and ththesults, along with word lengthl numben of neutrallzed vowels, and an andex of word familiarity, are used to predict worr location on the spelling LOCD. This allows the examination of the structure of fhe LOCD leading go greater understanding of the eeasons why spelling words are found to have particular difficulties, and dllowing gdaptation of the epelling LOCD to local conditions. A linearly ordered content domain (LOCD) is an array of related learning tasks positioned along a continuum according to the expected order in which they are learned (Bock, 1982). 1 As Bock (1982) pointed out, the description of the learner's attainment in terms of a position reached on the LOCD has important advantages over the more familiar concept of a content-referenced score, which was defined by Ebel (1962) as "a number