III Colloquium on Semi-Immersion in CataloniaIII Encuentro sobre Semi-Inmersión en CataluñaThis paper proposal presents an exploratory study in which the T-unit - the most popular unit of analysis applied in SLA research - was tested against FL learner empirical data. The aim was to investigate its appropriateness and effectiveness for the assessment of complexity of learners' academic explanatory oral production in the target language. Suggested by Hunt (1970) to measure schoolchildren' syntactic maturity in writing, it is defined as "a main clause plus all subordinate clauses and non-clausal structures attached to or embedded in it". The analysed empirical data were audio recordings of FL learners' individual pretests and posttests gathered during the implementation of a CLIL teaching sequence (Natural Sciences in English) in a Catalan state secondary school (Barcelona, Spain). In order to achieve the posed aim we followed a traditional SLA research practice in the area of written and oral learner discourse measurement and worked within the quantitative approach. Thus, the procedures to be taken were the following: (1) data segmentation into T-units according to the unit's definition and (2) data quantification by applying the T-unit to the data. For the latter, the chosen measures were: (a) two Frequencies (Unit Frequency and Unit Length Frequency) which could reveal the progress in general complexity and two Ratios (Clause Ratio and Subordinate Clause Ratio) which could provide information about syntactic complexity. However, already in the first phase of the analysis we were faced with several methodological problems related to the spoken nature of the data. First reason was the fact that the definition of the selected research tool turned out to be too wide and ambiguous when being applied to low-intermediate FL learner monologic spoken discourse. And secondly, having revised the studies on L2 and FL non-interactive production, we found very few ones that provided either guidelines for segmenting the data into T-units or any examples of their data segmented into analyzable units. Being especially interested in previous research made on the assessment of low level learners' explanatory spoken language complexity through the application of the T-unit, we found that none of the reviewed studies worked with the same type of the data and thus could serve as a reliable source for consulting. The analysis revealed that in the segmentation process the analytic tool resulted to be little appropriate for dealing with our data since it raised serious methodological issues which it was unable to resolve. In our opinion, this owes to the proper nature of the T-unit which was developed for the formal assessment of learner written syntactic maturity. However, in relation to the data quantification, the measures showed that the tool turned out to be useful not only in identifying the progress in complexity of the produced language attributable to the treatment but also in distinguishing between those who achieved this progress and those who did not. Still, to make any generalizations over the appropriateness and effectiveness of the selected tool both for data segmentation and measurement an examination of a larger corpus is highly recommended
