Educational interventions in school represent a primary way to introduce children to public health issues. In particular, as foodborne diseases are considered a worldwide significant problem, according to the World Health Organization (WHO), an educational program has been implemented to improve children knowledge about microorganisms’ characteristics and food contamination, and their everyday behaviors concerning personal hygiene. Twelve public schools in Padua province were enrolled, for a total of 249 children attending the fifth grade of primary school. Health programs are usually targeted to adults and teenagers; a method that take into account children's peculiar learning and communicative skills was adopted. Aim of the study is to determine whether interventions based on practical activities that dynamically involve children with experiments and scientific observations are more efficient that purely theoretical programs. To assess the different effectiveness of the interventions, a between subjects experimental design has been set up, with random assignment of classes to theoretical (N=120) and practical (N=123) groups. The evaluation of children knowledge was assessed in two ways: 1) the analysis of a questionnaire collected before and after the intervention; 2) the analysis of a creative drawing about the microorganisms collected before and after the intervention that has been related to a semi-structured interview, to comprehend the meanings of the picture. Results show that although both the programs (theoretical and practical) were effective, the practical work stimulated a qualitatively deeper comprehension of the given information, especially in relation to the causal linkage between protective behaviors and control of contagion risk.