National contest "Lithuanian naturalist" 1st-2nd form students' team (15) performed task (from animate nature and people's living environment sphere) analysis was carried out. The attention was paid to students' natural science knowledge and understanding. The research was grounded on the attitude that this contest as a non-formal education form is an effective device because it contributes to natural science education quality in primary school: (1) develops primary school students' natural science literacy; (2) makes possibilities for teachers to reflect on their experience and proposes ideas for the education process improvement; (3) for students -- future primary school teachers -- provides a possibility to acquire new experience (task creation, conducting theoretical and practical parts of the contest, preparation of evaluation instructions, students' work evaluation). [For the full proceedings, see ED619611.]