Studien utgår från en kvalitativt inriktad analys och metod, där syftet är att undersöka vilka huvudräkningsstrategier som 3 svenska respektive 3 engelska lärare undervisar i, inom addition. Det empiriska materialet består av intervjuer som sedan har transkriberats och analyserats. Studien har låtit sig inspireras av ett hermeneutiskt perspektiv kombinerat med Grounded Theory. Hermeneutiskt perspektiv innebär att all data som finns i studien har tolkats och analyserats. Grounded Theory är ett vanligt sätt att analysera kvalitativ data och genom denna teori har kategorier skapats utifrån det resultat som framkommit. Resultatet av studien visar att de svenska lärarnas vanligaste val av strategier är: talsorter var för sig och algoritmer. De engelska lärarnas vanligaste val av strategier är: tiokamrater, additionstabellen och algoritmer. Av resultatet framkommer även de skillnader som finns mellan de intervjuade lärarnas val av strategier. / The study is based on a qualitatively directed method and the main aim is to investigate, and examine the mental arithmetic strategies of both Swedish and English teachers. In particular, the methods they use, to teach addition. The empirical data within this research is based on first hand interviews with six teachers; three from Sweden, and three from England. The study is inspired by a Hermeneutic Perspective in combination with Grounded Theory. The word hermeneutic, means that all of the data contained in the study has been interpreted and analyzed by the researcher. Grounded Theory is a common method used to analyze qualitative data. With this theory, categories have been created on the basis of the results obtained within this study. The results of the study show that Swedish teachers' most common choices of strategies are; partitioning method, and algorithms. In contrast, the English teachers’ strategies are the following; number bonds, the additiontable and algorithms. The results of this study also illustrate the differences between the Swedish and the English teachers’ choices of strategies.

Στόχος της παρούσας έρευνας ήταν να διερευνηθούν οι επιδόσεις και τα είδη των στρατηγικών που χρησιμοποιούν οι μαθητές της Δ΄ τάξης του δημοτικού σχολείου, με και χωρίς μαθησιακές δυσκολίες στα μαθηματικά (ΜΜΔ), όταν υπολογίζουν νοερά προσθέσεις και αφαιρέσεις διψήφιων αριθμών και να διαπιστωθεί αν υπάρχει αξιόλογη διαφορά στην επίδοση μεταξύ των μαθητών αυτών. Προηγούμενες μελέτες που αφορούν στις ΜΜΔ έχουν ασχοληθεί με τις απλές (π.χ. 3+5) και όχι με τις διψήφιες νοερές προσθέσεις και αφαιρέσεις. Στην παρούσα έρευνα συμμετείχαν 85 μαθητές (40 με ΜΜΔ και 45 κανονικής επίδοσης στα μαθηματικά-ΚΕ), όπως προέκυψε από την αξιολόγησή τους με σταθμισμένες και μη δοκιμασίες. Επιπλέον, στους μαθητές αυτούς χορηγήθηκε δοκιμασία στους νοερούς υπολογισμούς. Τα αποτελέσματα της έρευνας έδειξαν ότι οι μαθητές ΚΕ χρησιμοποιούν, κατά κύριο λόγο, στρατηγικές υψηλού επιπέδου (αυτές που συντελούν στην καλύτερη κατανόηση των αριθμών) τόσο στην πρόσθεση όσο και στην αφαίρεση. Παρόλα αυτά, η χρήση στρατηγικών υψηλού επιπέδου είναι πιο έντονη στην πρόσθεση συγκριτικά με την αφαίρεση, γεγονός που υποδηλώνει τη δυσκολία της αφαίρεσης ως πράξη. Επιπλέον, οι αφαιρέσεις με κρατούμενο είναι πιο δύσκολες από αυτές χωρίς κρατούμενο και για τις δύο ομάδες. Επίσης, τα αποτελέσματα έδειξαν ότι οι επιδόσεις των μαθητών με ΜΜΔ γενικά σε όλες τις πράξεις είναι χειρότερες από αυτές των μαθητών ΚΕ. Τέλος, οι μαθητές με ΜΜΔ υπέπεσαν σε περισσότερα λάθη σε σχέση με τους μαθητές ΚΕ, ανάλογα με το είδος της πράξης, αλλά και σε περισσότερα είδη λαθών. Τα περισσότερα λάθη των μαθητών εντοπίστηκαν κυρίως στις αφαιρέσεις με κρατούμενο, όπου είτε αφαιρούσαν τις μονάδες του μειωτέου από τις μονάδες του αφαιρετέου είτε έκαναν κάποιο λάθος στο δανεισμό. Περαιτέρω έρευνες είναι απαραίτητες προκειμένου να διαπιστωθούν οι διαφορές που εντοπίζονται στην επίδοση, τις στρατηγικές και τα λάθη μεταξύ των παραπάνω μαθητών στις διψήφιες νοερές προσθέσεις και αφαιρέσεις. / The purpose of the present study was to investigate the performance and the kinds of strategies that students, with and without mathematical learning disabilities (MLD), attending fourth grade of elementary school (9 years old) use when they add and subtract two-digit numbers mentally and to find out whether there is any notable difference in the performance between these groups. Previous studies related to MLD have dealt with simple mental additions and subtractions (eg 3+5) and not with two-digit calculations. Eighty five students participated in the present study (40 with MLD and 45 normally achieving students – NA). All students completed tests, which evaluated their mathematical skills. The results from these tests led to the selection of the students that would form each one of the two groups. Moreover, students of both groups were assessed on a mental calculation task. The results of the study indicated that NA students tend to use sophisticated strategies (those that contribute to a better understanding of numbers) both in addition and subtraction. However, the percentage of sophisticated strategies appeared to be higher in addition than in subtraction, a fact that implies there is a particular difficulty in subtractions. Moreover, this study found that subtractions, which involve regrouping procedures (such as “carrying” or “borrowing”), are more complex than others for both groups. Furthermore, the results showed that the performance of MLD students on mental calculation tasks was worse than NA students. Last but not least, MLD children made more errors than NA children depending on the type of operation and they made more types-categories of errors than NA children. Most errors were made in subtractions with carrying digit. There either they subtracted minuend’s units from subtrahend’s units or they made an error with the carrying digit. Further research is necessary in order to investigate the performance and the kinds of strategies that students, with and without mathematical learning disabilities when they add and subtract mentally two-digit numbers.

This study was conducted to analyse aspects of mental computation within primary school mathematics curricula and to formulate recommendations to inform future revisions to the Number strand of mathematics syllabuses for primary schools. The analyses were undertaken from past, contemporary, and futures perspectives. Although this study had syllabus development in Queensland as a prime focus, its findings and recommendations have an international applicability. Little has been documented in relation to the nature and role of mental computation in mathematics curricula in Australia (McIntosh, Bana, & Farrell, 1995,p. 2), despite an international resurgence of interest by mathematics educators. This resurgence has arisen from a recognition that computing mentally remains a viable computational alternative in a technological age, and that the development of mental procedures contributes to the formation of powerful mathematical thinking strategies (R. E. Reys, 1992, p. 63). The emphasis needs to be placed upon the mental processes involved, and it is this which distinguishes mental computation from mental arithmetic, as defined in this study. Traditionally, the latter has been concerned with speed and accuracy rather than with the mental strategies used to arrive at the correct answers. In Australia, the place of mental computation in mathematics curricula is only beginning to be seriously considered. Little attention has been given to teaching, as opposed to testing, mental computation. Additionally, such attention has predominantly been confined to those calculations needed to be performed mentally to enable the efficient use of the conventional written algorithms. Teachers are inclined to associate mental computation with isolated facts, most commonly the basic ones, rather than with the interrelationships between numbers and the methods used to calculate. To enhance the use of mental computation and to achieve an improvement in performance levels, children need to be encouraged to value all methods of computation, and to place a priority on mental procedures. This requires that teachers be encouraged to change the way in which they view mental computation. An outcome of this study is to provide the background and recommendations for this to occur. The mathematics education literature of relevance to mental computation was analysed, and its nature and function, together with the approaches to teaching, under each of the Queensland mathematics syllabuses from 1860 to 1997 were documented. Three distinct time-periods were analysed: 1860-1965, 1966-1987, and post-1987. The first of these was characterised by syllabuses which included specific references to calculating mentally. To provide insights into the current status of mental computation in Queensland primary schools, a survey of a representative sample of teachers and administrators was undertaken. The statements in the postal, self-completion opinionnaire were based on data from the literature review. This study, therefore, has significance for Queensland educational history, curriculum development, and pedagogy. The review of mental computation research indicated that the development of flexible mental strategies is influenced by the order in which mental and written techniques are introduced. Therefore, the traditional written-mental sequence needs to be reevaluated. As a contribution to this reevaluation, this study presents a mental-written sequence for introducing each of the four operations. However, findings from the survey of Queensland school personnel revealed that a majority disagreed with the proposition that an emphasis on written algorithms should be delayed to allow increased attention on mental computation. Hence, for this sequence to be successfully introduced, much professional debate and experimentation needs to occur to demonstrate its efficacy to teachers. Of significance to the development of efficient mental techniques is the way in which mental computation is taught. R. E. Reys, B. J. Reys, Nohda, and Emori (1995, p. 305) have suggested that there are two broad approaches to teaching mental computation,,Ya behaviourist approach and a constructivist approach. The former views mental computation as a basic skill and is considered an essential prerequisite to written computation, with proficiency gained through direct teaching. In contrast, the constructivist approach contends that mental computation is a process of higher-order thinking in which the act of generating and applying mental strategies is significant for an individual's mathematical development. Nonetheless, this study has concluded that there may be a place for the direct teaching of selected mental strategies. To support syllabus development, a sequence of mental strategies appropriate for focussed teaching for each of the four operations has been delineated. The implications for teachers with respect to these recommendations are discussed. Their implementation has the potential to severely threaten many teachersf sense of efficacy. To support the changed approach to developing competence with mental computation, aspects requiring further theoretical and empirical investigation are also outlined.