In the fight against foodborne diseases, expanding access to information for different groups is needed. In this aspect, it is crucial to evaluate the target audience’s particularities. This study constructed and validated an instrument containing three questionnaires to identify the level of knowledge, practices, and risk perception of food safety by low-income students between 11 and 14 years old. The following steps were used: systematic search of the databases; conducting and analyzing focus groups; questionnaires development; and questionnaires analysis. After two judges’ rounds, the final version was reached with 11 knowledge items, 11 practice items, and five risk perception items. The content validation index values were higher than 0.80. The adopted methodology considered the students’ understanding and perceptions, as well the appropriate language to be used. Besides, it allowed the development of questionnaires that directly and straightforwardly covers the rules set by the World Health Organization for foodborne disease control called Five Keys to Safer Food (keep clean; separate raw and cooked; cook thoroughly; keep food at safe temperatures; and use safe water and raw materials). Its use can result in a diagnosis for elaborating educational proposals and other actions against foodborne illness in the most vulnerable population.