Abstract
The aim of this empiric paper is to (1) introduce the pupil's preconception as a constitutive component of L1 instruction, (2) on the concrete example of the sentence element of grammatical modifier show that understanding the pupil's preconception as a key determinant of instruction is not only relevant, but truly necessary; (3) suggest which direction further research and instruction improvements might have. The first part defines the key concepts - notion, preconception, conception - and analyses their place in L1 instruction.
Then it shows the critical areas in Czech language and Czech syntax instruction, the last part presents the authors' research. Through random stratified sampling a sample of pupils in the first year of upper secondary school was created.
Through the method of individual interview using specially designed exercises pupils' preconceptions of the grammatical modifier were researched. The results suggest that pupils have the conception of the grammatical modifier and also low-achieving pupils are able to verbalize it and describe it precisely.
However, after introducing terminology, with some pupils a bloc imposed by education and a clash between natural perception of language and its grammatical description appears. Pupils also start thinking differently - their spontaneous contemplations stop and they start using inappropriate mechanical strategies taught at school.
The study also draws attention to the persisting problem - instruction introduces terminology too early and does not link it to the pupil's natural language competence and communication experience. Despite the unsatisfactory mastering of fundamental knowledge it advances, which creates the vicious circle of failure.