This study brings results of the first phase of research probe that monitors relation between the metacognition of pupils of secondary school and level of their writing. Qualitative research probe is focused on the pupils aged 14 to 15 and is based on the continuous monitoring of individual pupils. During the research, respondents worked with several monitoring and diagnostic tools. Research activity had also anexperimental nature and supported pedagogical-educative process among the monitored group of pupils – it significantly influenced course of the classes (respecting the processual nature of writing) and approach to particular pupils, mainly within the area of diagnostics and evaluation.