## 2 Materials and Methods
### Methodology
Both assessments distinctly classify the dependent variables as quantitative ratio variables, wherein net attention can range from 0 to 60, impulsivity control can vary from 0 to 100, and figurative creativity can extend from 0 to approximately 300. * For the 'instrumental learning' variable: Andalusian regionally standardised assessments in language (restricted to the dimensions of written expression and comprehension) and mathematics, although modified to align with the expected duration of the tests [51; 52; 53; 54; 55], were used. The level of the mathematical competence test was maintained at a maximum of 13 points, while the linguistic competence test allowed a total of 34 points, 22 of which corresponded to written expression and 12 to written comprehension. * For the variable 'affective processes': A questionnaire integrating the foundational study by [PERSON] et al. [3], composed of three self-perception questions (two Likert-scaled out of a score of ten and one nominal), was used. For the statistical coding of the final question, we used the conversion criteria outlined in Table 1.  
The research framework, as noted above, adheres closely to the 'equivalent materials design' articulated by [PERSON] et al. [46] in two of the experimental contexts, thus ensuring a high degree of internal validity despite certain limitations in external validity, as acknowledged in the authors' theoretical framework. In contrast, the initial context, exploratory research characterised by an incomplete counterbalanced design (as mentioned above), demonstrates reduced rigour, although the measures outlined below were similarly applied. To improve this validity, efforts were made to mitigate extrane  
Figure 2: Complete summary of variables (dependent and independent) and their constituent dimensions that make up the study. was recognised that complete isolation of such variables was unfeasible, particularly in the standardised classroom environment where the assessments were administered:  
* To mitigate the influence of weather factors on the lighting conditions, we mitigated their effects while ensuring that students did not experience a sense of confinement resulting from the absence of natural light. * To increase the sample size (which was limited in the initial counterbalanced structure), we administered tests to all participants in the experimental cohort on a daily basis in experimental conditions 2 and 3, thus foregoing the counterbalanced approach. * The introduction of coloured lighting took place one month before the start of data collection in each experimental situation, thus integrating it into the usual activities of the educators in the classroom on a daily basis at the choice of the educators themselves. In this way, the students became accustomed to the exposure to coloured light, so that after one month the experimental tests were approached as normally as possible. In this way, we were able to alleviate possible biases of the 'Hawthorne' motivation effect. * To reduce the learning effect, according to [PERSON] et al. [35], the experimental situations were approached by scheduling the data collection of the different light scenarios with a spacing of two weeks, trying to reduce the students' memory of the tests. In addition, to avoid any alteration of students' behavioural and emotional responses, the purpose of the study was not disclosed, and all activities were framed within the usual classroom practices. * To further minimise recall biases, in experimental conditions 2 and 3, the sequence of the 'coloured light' scenarios was modified.