Recruitment and participants
Participants in this project were Danish school children from 2nd to 6th grade. The participating children were between 8 and 12 years of age (mean = 9.86, SD = 1.47) and 54.3% were female. The children were recruited through cooperation with schools and municipalities across the region of Sealand in Denmark. Efforts to ensure representability of the general Danish population in terms of socioeconomic background and ethnicity were made by including schools from neighborhoods with different proportions of citizens with low socioeconomic status. The schools were recruited by authors PSM and MK by contacting schools directly or through municipalities. The physical education teachers in the schools were offered to have their pupils go through the assessment tool as part of their physical education teaching schedule (corresponding to two modules of physical education classes). In total, 19 schools were contacted of which 14 agreed to participate and two withdrew because of COVID. The final sample included 891 school children from 50 classes in 12 schools.
Translation and pilot testing
The CAPL-2 questionnaires were translated into Danish language and adapted to the Danish context. For this purpose, a protocol inspired by the World Health Organisation (WHO) protocol for translation and adaptation of instruments  was developed. The protocol was divided into four phases.
Phase 1: forward translation
Two independent Danish researchers with a degree in sport and exercise science and with Danish as their first language translated the questionnaires as well as the protocols for physical testing. The translated documents were compared and combined into one document by a third independent translator with expertise in sport and exercise science and Danish as a first language.
Phase 2: expert panel back-translation
The final translated Danish version was reviewed and back-translated into English by a translator with English as a first language and international expertise in sport and exercise science. This version was compared to the original version by the research group and discrepancies were identified. All members of the research group reviewed the discrepancies and made changes accordingly. The final version was then reviewed by practitioners with experience in teaching physical education and Danish in primary school, to improve understanding of the questions for the age group and further linguistic adjustments were made.
Phase 3: pre-testing and cognitive interviewing
The physical tests (i.e. CAMSA, PACER and plank isometric hold; please see section on CAPL-2-related measures later) were pilot tested on 2 second grade classes (the lowest grade included in the sample) at one school. The lowest grade was chosen because it was expected that the youngest children would use the most time filling in the questionnaires as well as doing the physical testing. Therefore, if the practical plan worked in these grades it would be a good indication that it would work in all grades. Hence, based on the pilot in the second grade, solutions to the practical issues of how to administer the different tests within a Danish physical education setting were developed. The questionnaire items were also pilot tested in the same class. The questionnaires were administered, response distributions were inspected, and the following week cognitive interviewing was performed with all children. Here using the lowest grade was also optimal because it was expected that if understandability was achieved in the youngest grade this would also be high in the older classes. At the interviews, the children’s verbal answers were compared to the answers they gave in the questionnaires and they were given the possibility to identify words or concepts they found hard to understand. Based on the feasibility from the pilot, the research group changed the distribution type of the questionnaires, which was originally distributed on paper and administered by a teacher. Hence, the final version of the questionnaire was video-assisted (pictures and audio), so the children could watch and answer on their own on a tablet or computer.
Phase 4: final decision making
Finally, the project group went through all previous steps and made decisions on the final translation of the descriptions of the physical tests as well as the questionnaire items. A final version of questionnaire items and manual description was decided upon.
As described briefly in the introduction, CAPL-2 measures PL in four domains: Motivation and Confidence, Physical Competence, Knowledge and Understanding, and Daily Behavior. The domains are measured through a series of questionnaires, cognitive and physical tests, and direct monitoring of daily step counts which when completed are converted into a score ranging from 1 to 100. Detailed descriptions as well as videos with instructions of each protocol for measuring the components within each domain can be found in the CAPL-2 manual, which is available on the CAPL website (https://www.capl-eclp.ca/).
The Motivation and Confidence domain is measured with a 12-item questionnaire. The questionnaire aggregates to four subscales: predilection, adequacy, intrinsic motivation and self-confidence. Each subscale is measured with four items.
Physical Competence is measured with three different physical tests. 1) The plank isometric hold that measures torso muscular endurance , 2) the Progressive Aerobic Cardiovascular Endurance Run (PACER), an aerobic fitness test which measures the children’s aerobic capacity , and 3) the Canadian Agility and Movement Skill Assessment (CAMSA), which is a dynamic motor skill test developed for children aged 8–12 years of age .
The Knowledge and Understanding domain is measured with the Physical Literacy Knowledge Questionnaire (PLKQ) , which measures PL-related knowledge, based on the Canadian school curricula. It involves four multiple choice quiz items with four response possibilities. There is one correct and three incorrect answers for each item. Lastly, children complete a comprehension test in form of a ‘fill in the blank’-task where they fill in six blank spaces in a short story about concepts related to PA. All questionnaires are available on the CAPL-2 website.
The Daily Behavior domain is measured with one self-report item of weekly participation in moderate- to vigorous-intensity physical activity and objectively measured average step count for 1 week. Week average of step counts was measured with an AX3 Axivity accelerometer (Ltd., Newcastle upon Tyne, United Kingdom) instead of a pedometer as described in the original CAPL-2 protocol. This was done in order to increase compliance as this method has previously been used with success in a Danish context  and accelerometers have been validated in children to measure physical activity, including step counts, with great success . The monitor was affixed on the mid-anterior aspect of the left thigh using a taping method , which enable full 24-h recording, since it allows the participant to bath and swim with the monitor attached. Participants were instructed to reinforce the original tape, as required to avoid it from falling off. The measurement period was the week in between the two physical education classes.
Physical education teacher rating
To be able to investigate the predictive validity of the Danish version of the CAPL-2, the children’s physical education teachers were asked to rate their pupils on a scale from “1. not true at all” to “10. completely true” on four characteristics, which theoretically should be associated with children’s PL . In all four items, the physical education teachers were asked to rate the child compared to their peers. The four items were (here presented in as direct translation from Danish to English as possible) “The pupil’s motor skills are generally good”, “The pupil seems to enjoy physical education”, “the pupil shows a high degree of self-confidence during physical education” and “the pupil is skilled in many different types of sport and exercise activities”. A composite score of the pupil’s total teacher rating was calculated as the average of the four items.
The different measurement protocols of the CAPL-2 were administered during two physical education classes 1 week apart. During the first class, the children completed the CAMSA test, answered the questionnaires of the Motivation and Confidence domain and the cognitive test for the Knowledge and Understanding domain. The second class, the children completed the plank isometric hold and PACER test and answered some additional questionnaires. All physical tests where administered by the research group and trained student research assistants. In between the two classes, the children wore an Axivity AX3 accelerometer continuously. During data collection, the children were divided into three or four groups that alternated between the physical tests and answering the questionnaires and the cognitive tests.
To help the children who had difficulties reading, a video where all items of the questionnaires were read out loud, while the text appeared on the screen, were made. This was embedded in the electronic questionnaire set up in the survey program SurveyXact (Rambøll Management.
Consulting, version 6.10 Copenhagen, Denmark). The participants filled in the questionnaires on a computer or a tablet while wearing headphones. A positive side-effect of wearing headphones was that the participants were quiet and did not interfere with each other while filling in the questionnaires. If necessary, the teacher assisted the children.
Study procedures were approved by The Capital Region’s center for data reviews “Videnscenter for Dataanmeldelser” (Reference: P-2019-659). In Denmark, only biomedical research and research projects that entail a risk for participants can receive a Trial Registration Number through ethics review by a Regional Ethics Board. The Regional Ethics Board have assessed that the project is not notifiable (journal number:19088122). All methods were carried out in accordance with relevant guidelines and regulations. Written information about the study was given to all school principals, teachers and parents/guardians before the start of the study, and informed consent was obtained from the legal guardians of all participants. The pupils themselves also had the option of withdrawing from the project upon request.
To assess internal consistency of psychometric scales, within the Motivation and Confidence domain, robust Cronbach’s alpha was calculated as well as for the entire Motivation and Confidence domain for which the omega reliability measure was also calculated. Reliability measures were computed with the R package ‘coefficientalpha’ . Values above .7 were considered acceptable .
Construct validity was examined by conducting confirmatory factor analyses. The analyses were done in Mplus . The nested structure of the data was accounted for by specifying the variable school class in the function cluster. Maximum likelihood estimation with robust standard errors (MLR) was used and type was set to complex. The following criteria for an acceptable model fit was used: Chi-square/df < 5.00, comparative fit index (CFI > .95), Tucker-Lewis index (TLI > .95), root mean square error of approximation (RMSEA<.06) and root mean square residual (SRMR<.08) . If an unacceptable model fit was reached, inspection of modification indices informed model fit improvements by either removal of poor indicators or by allowing correlations between error terms of indicators within a domain. Mplus code can be supplied upon request.
The predictive validity of the CAPL-2 was investigated by conducting five regression models with teacher rating of the pupils as outcomes and each of the domains as well as the total CAPL-2 score as predictors. The teacher ratings and PL were hypothesized to be associated, and this association was used as an indication of predictive validity as the indicators that the physical education teachers rated their pupils on have been argued as central characteristics and outcomes of PL .