Krølner et al. BMC Public Health 2012, 12:191 http://www.biomedcentral.com/1471-2458/12/191 efforts were reviewed to identify tutorials which addressed the selected target determinants [62-68]. Materials were adapted to the study purpose and target group. New tutorials were developed if tutorials were not available or inadequate. A first draft was discussed with two home eco- nomics teachers regarding appropriateness for the target group and feasibility for teachers, and revised accordingly. A second draft was presented for teachers from interven- tion schools at the one-day workshop for their feedback and to stimulate local ownership to the material. A third revised version was reviewed by two teachers at a college for education to estimate the necessary preparation time for teachers for each tutorial and to specify the national learning objectives met by different tutorials. This infor- mation was included in the final version of the material. Finally, a graphic designer set up an appealing material. Computer tailored feedback Computer tailoring appeal to adolescents [39]. The Boost computer tailored feedback messages were tailored to the 13-year-olds’ FV intake, awareness levels, taste preferences, and leisure time activities. The Boost computer tailoring program was designed to meet four purposes: 1. Raising awareness of own FV intake. The adolescents were to complete the test three times over the course of the intervention. Their answers were stored in the system, so they could monitor their own intake over time (ipsative feedback). 2. Changing FV taste preferences. The personal feedback suggested recipes to try FV, the 13-year-olds had reported they did not like, in a new way. 3. Changing situational norms for eating FV. The perso- nal feedback message contained ideas to eating FV with friends and at leisure time activities. 4. Process evaluation: The program featured questions about 13-year-olds’ usage of the free FV delivered by Boost, including reasons for not eating it. Pupils were asked to complete the program in the beginning, middle and end of the intervention period, favouring a more detailed description of intervention dose. The pupils logged into the computer tailoring module by a personal identification number leaving the possibility to merge the computer tailoring data with data from baseline and follow-ups. Development of Computer tailoring The Boost computer-tailored program was designed using TailorBuilder version 1.8 developed by OverNite Software Europe BV [69]. The Boost computer-tailored program was based on the Norwegian version of Pro Children com- puter tailoring for 11-year-olds [64]. Four year 7 pupils (two girls and two boys) were asked to test and comment on the Norwegian version. This version was translated into Danish, adjusted to fit with the older target group and new questions and feedback messages were developed. This Boost version was pilot-tested among five year Page 10 of 25 7 pupils (three boys and two girls) who participated in a focus group to once more examine comprehension, appeal, layout and the relevance of questions, answer cate- gories and personal feedback. Based on this pilot study a final version was developed and pretested among collea- gues before the program was launched at intervention schools. Home component Parent school meetings At the beginning of the intervention period (August/Sep- tember 2010) the Boost project was presented at parent meetings at 18 intervention schools. The parents were encouraged to support their teenagers in eating FV and to participate in the curricular activities (teenager-parent home assignments). As the parent meetings coincided with the baseline data collection, we left out advice on how to increase FV intake among adolescents to avoid influencing the parents’ responses to the baseline ques- tionnaire. The information was later included in a newsletter. Parental newsletters Parents received six newsletters in the intervention period. The purpose of the parental newsletters was to give ideas of how to serve more FV in their families, as well as to inform parents of the Boost activities in school (Table 3). We used literature on parental barriers for eating and ser- ving FV to adolescents [70-73] and brainstormed on ideas for content with a 6 a day campaign leader [68]. The newsletters were decided to target the following modifiable determinants: home availability (variety), home accessibil- ity (parental facilitation), 13-year-olds’ access to FV at sports-and youth clubs, parental knowledge, parental intake and perceived parental barriers for making FV avail- able to children at home (price, time costs, concerns regarding whether FV can satisfy hungry teenagers’ appe- tite, food preparation skills, family taste preferences, and choosiness of teenagers). The newsletters were set up by a graphic designer and pre-tested among colleagues with children in year 7 to ensure the relevance and quality. The local coordinators at each school were asked to post the newsletters at the school’s website for parents (parental intranet). School event As part of the FV project week schools were encouraged to invite parents to experience the on-going Boost curri- cular activities at an event organised by the 13-year-olds. Teenager-parent assignments The pupil workbook included assignments to complete at home together with the family. The purpose was to target pupil-perceived availability and stimulate a family discussion about the 13-year-olds’ and the family’s favourite FV to influence future FV purchases. The assignments were followed up by discussions in class on