To evaluate a web-based nutritional knowledge questionnaire for primary-school children.

Children's nutritional knowledge was assessed in five domains: healthy choices (twenty-seven items), estimated recommended portions/servings (eight items), nutrient content (five items), main food function (five items) and categorization of food items (eight items).

The questionnaires were completed in school.

A convenience sample of 576 Belgian children (aged 7–12 years) from fourteen primary schools completed the questionnaire once, 386 completed the questionnaire twice.

Healthy choices could be answered correctly by 73 % of the children, nutrients by 59 %, food categorization by 49 %, main function by 38 % and portion estimation by 36 %. Children's test–retest intra-class correlations were 0·75 for healthy choices, 0·33 for nutrients, 0·61 for food categorization, 0·44 for main function, 0·47 for portion estimation and 0·76 for the total scale. The intra-class correlation was lower in the youngest age group (grade 2: 0·51, grade 4: 0·65, grade 6: 0·66). The total score was significantly lower in the retest. The instrument was in general positively evaluated by the children.

The instrument is a promising, practical, inexpensive tool with acceptable test–retest reliability in fourth and sixth graders.

To investigate test–retest reliability of primary-school children's reports of food preferences and to investigate agreement with parental reports.

Children completed an online test and retest, one to two weeks later, during school hours; parents completed a paper-and-pencil or an online questionnaire at home. The children's preferences questionnaire contained 148 food items, reduced to twelve scales; the parental questionnaire contained seventy-eight items reduced to nine scales.

Children of fourteen primary schools in Belgium-Flanders.

In total 572 children participated; test–retest data were available for 354 children, children's tests could be matched to 362 parental reports.

Test–retest intraclass correlations were on average 0·73, ranging between 0·62 and 0·86; correlations between children's and parents’ reports were on average 0·50, ranging between 0·32 and 0·62. Retest preferences were significantly higher for more than half of the scales. Children reported higher preferences than their parents for milk & milk products, fruit and soft drinks, while parents reported higher preferences for bread & breakfast cereals, meat, snacks and sauces.

The results indicate that the test–retest stability was good; however, agreement between parents and children was rather low to moderate.