Measuring HL in adolescent students: a preliminary report on the development of a task- and skills-based assessment instrument for use in educational settings

Health Literacy (HL) refers to personal competencies for accessing, understanding, appraising, and applying health-relevant information in order to make sound decisions in everyday life that promote the prevention of bad and maintenance of good health. Schools are seen as promising intervention settings for promoting these skills in adolescents. School testing that reflects health-related tasks that students need to complete in daily life stands the best chance of promoting growth in HL. Testing can facilitate the transfer of learning, i.e. the application of previous learning in the solution of novel problems in different contexts. This study presents a newly developed performance-based instrument for the measurement of HL knowledge and skills in adolescents in a school-based context, as well as the results of a validation study. The instrument aims to measure adolescents’ generic HL and takes account of competency-based principles of education. The results of the validation study prove the reliability, measured by Cronbach’s alpha, and construct validity (expert panel and factor analysis) of the newly designed instrument. The study also demonstrates that the instrument can distinguish between weaker and stronger students.


Introduction
Health Literacy (HL) is an important health promotion concern.Its importance can be derived from the fact that governmental bodies around the world have released national action plans to promote HL in citizens (e.g., the EU's European Health Literacy Action Plan [1]; CDC's National Health Education Standards [2]; Germany's Nationaler Aktionsplan Gesundheitskompetenz [3]).The implementation of such action plans requires the cooperation of different societal domains, such as the political and healthcare domain.It has also been recognized that education has a critical role to play in the achievement and maintenance of HL over the life course [4].In recent policy documents, the World Health Organisation has emphasized the need to monitor HL in order to identify the current state of HL in various population groups, such as adolescents [5].This will provide a starting point for data-driven policies, and for practical interventions targeted at HL development, also in education.
Indeed, education is now seen as a tool for empowering people to independently manage their lives in healthy ways.Through a focus on skills development and empowerment, school education has a distinct influence on the purpose and focus of HL education.The focus is on task-based education, designed to develop specific skills to manage prescribed health management activities (medication adherence, behavior change).It is also skills-based, with educational activities that are designed to develop generic, transferable skills that equip people to make more autonomous decisions relating to their health and allow them to adapt to changing circumstances (9, p. 708).
The way in which HL has been defined has changed over the years.In 2012, Sorensen and her colleagues [7] presented a systematic review of HL definitions and models.Their review resulted in 17 definitions of HL and 12 conceptual models.Based on their analysis, they proposed an integrated conceptual model containing 12 dimensions referring to the knowledge, motivation and competencies needed to access, understand, appraise and apply health-related information within the healthcare, disease prevention, and health promotion setting, respectively (Sorensen et al. [7], Fig. 1).In 2000, Nutbeam in his seminal article [8], conceptualized HL as comprising functional HL, interactive HL, and critical HL.The functional domain refers to basic skills in reading and writing health information, which are important for functioning effectively in everyday life.The interactive domain represents advanced skills that allow individuals to extract health information and derive meaning from different forms of communication.The critical domain represents more advanced skills that can be used to critically evaluate health information and take control of health determinants ( [9], p. 2).In 2006, Baker [10] distinguished between health-related print literacy and health-related oral literacy, which were both fed by health-related reading fluency, health-related vocabulary, and familiarity with health concepts.Fleary [11], more recently, has emphasized the critical engagement with health-related (digital) media content as a subskill of HL.Indeed, in some (leading) countries, HL as a concept is now starting to move away from a small focus on literacy for the management of one's disease in healthcare settings to a much broader conceptualization, including generic skills and competences to deal with any health-related information in critical ways to the benefit of disease prevention and health promotion.
Although HL can now be considered as sufficiently explained in terms of its definitions and theoretical models, its measurement remains a contested issue, also in education.Over the past two decades, children's and adolescents' HL and its assessment have been the focus of increased academic attention [9,[12][13][14][15][16][17].Compared to the wider availability of instruments for adults, only a few tools are known for younger age groups, and many of these tools are self-report instruments, not performance-based tools where test takers have to provide proof of their abilities.These tools include, for example, the REALM-Teen (Rapid Estimate of Adolescent Literacy in Medicine), the HLAT-8 (HL Assessment Tool), the SAHLSA-50 (Short Assessment of HL for Spanish-speaking Adolescents), the AHLI (Adolescent HL Instrument), the HLQ (HL Questionnaire), the CAHLQ (Child and Adolescent HL Questionnaire), or the HELMA (HL Measurement for Adolescents).Some tools were originally designed for adults (e.g., TOFHLA; HLQ, NVS), but have then been adapted for use Fig. 1 HL: a conceptual framework (Baker [10], p. 879)).Reprint with permission with children and/or adolescents.After a systematic review of child and adolescent HL measures for field use, Guo et al. [9], who based their review also on Ormshaw et al. [18] Perry's [19], and Okan et al. [20] reviews of child and adolescent measurements of HL, suggest that they found the HLAT-8, the 8 item HL Assessment Tool, the most suitable tool to measure childhood and adolescent HL and want to advocate its use in future research.Yet, tools that are fit for use in research, are not necessarily also suitable in educational contexts, as stimuli for and assessment instruments of learning.The HL measurement instruments used in research may not reflect the tasks set to students for educational purposes.Also, tools that have been developed for education within one particular cultural context (e.g., [11]) may not be culturally appropriate for another context.
Even if there is a lot of value in the above-mentioned tools, especially within the medical setting or situations where a rapid estimate of HL is needed, it is more difficult to meaningfully use these instruments in an educational setting, where testing and learning need to go hand in hand [21], and the curriculum, instruction, and assessment need to be aligned ( [4], p. 7).The core business of today's education is to promote knowledge, and especially transferable task-based and generic skills in young people that can be transferred to new situations, also in relation to HL.Consequently, a need has arisen for HL measurement instruments that can map these skills in learners.
Indeed, teachers need tools that allow them to assess objectively to what extent students have acquired HL in terms of the knowledge and skills that make up HL.They cannot use self-report instruments where students indicate to what extent they themselves believe they master particular skills.Teachers need objective ways to assess students, where students have to perform and carry out tasks, and on the basis of task execution can be said to have or have not yet achieved an attainment target of secondary education, such as HL.
Educational tasks reflect the generic competencies students need to develop in the course of their secondary education.The core business of schools is to provide students with the knowledge they need to be functional adults in their day-to-day lives.They need to know how to read, write, and do arithmetic.They also need to be able to assess any information presented to them via different (digital social) media in critical ways, building on the knowledge they have acquired so far and adding correctly retrieved reliable information to their existing knowledge base so as to become more resilient citizens.
To promote and assess learning, it is vital that education disposes of instruments that measure learners' HL in reliable and valid ways so as to establish a baseline level on which to build educational policies.Indeed, in order to be able to educate adolescent learners and meet them where they are in their development, it is essential to establish young people's current level of HL.How much knowledge do they have, for example, of the health care system?Can they read and understand patient package inserts, for example, to learn about adverse effects when taking a particular medicine?Are they able to discern between trustworthy medical websites and commercial ones on the Internet?In other words, the assessment instrument needs to measure students' knowledge, information literacy, media literacy, and critical thinking.It needs to be able to establish to what extent young people are able to find, appraise and apply (digital) health information, make informed decisions about their health, and inform their health behavior forever more autonomously and independent of parents and other caretakers.
This paper describes the development of an objective competency-based instrument to assess adolescents' HL in a school context.The developmental process consisted of the following phases: (i) the choice of a theoretical framework on which to build the instrument; (ii) item development; and (iii) a validation study (N = 132).

Development of HLQE (HL Questionnaire for Education)
In what follows, we first present the theoretical basis on which our instrument is built.Next, we describe how items were generated and selected.Thirdly, we report the results of a validation study.

Theoretical foundation
In an educational context, attainment targets are formulated foremost in terms of knowledge, skills, and attitudes.Teaching and assessment thus also need to reflect these dimensions.From Baker's ( [10], p. 879) conceptual framework (Fig. 1), it can be seen how this could be done for HL.Baker defines HL in terms of knowledge, abilities, and attitudes which together will improve health outcomes.Medical jargon or vocabulary is seen as an important knowledge component, as is conceptual knowledge of health and healthcare.Skills include reading fluency, the ability to understand written and oral health information, and the ability to orally communicate about health.As pupils learn new information from written texts, they learn new knowledge and develop positive attitudes toward health promotion and health prevention and start to feel more confident to complete health-related tasks.
After Baker, many authors have tried to update the definition of HL.One now commonly accepted comprehensive definition of HL at the individual level runs as follows: HL can be defined as having the capacities, skills, knowledge, and motivation to access, understand and apply relevant health information in different forms, in order to make judgments, take decisions and act in everyday life in the domains of healthcare, disease prevention, and health promotion to improve quality of life (and health) throughout the life course [7,22].In this definition which is also used in educational contexts, it is implied that information literacy, functional literacy, media literacy, and critical thinking skills are part of HL.This definition is reminiscent of Nutbeam's 2000 [8] distinction between functional and interactive HL, which in 2019 [6], he revisited to include more explicitly the ability for task-based communication and skills-based problem-solving, giving changing contexts."Health education has to continue to evolve to reflect these changes [e.g., the rise of new media with enhanced complexity of communication; realization of environmental determinants of health], to enable people to navigate competing sources of information and to engage meaningfully with social and economic determinants of health, as well as respond to personal risks.Health education has to help people develop transferable decision-making skills and not just achieve compliance with pre-determined health goals" (Nutbeam, [6], p. 709).
The instrument we propose reflects Bakers' oral and written HL competencies that are fed by reading fluency and prior vocabulary and conceptual knowledge, as well as the three skills dimensions (functional, interactive, critical) proposed for education by Nutbeam [6,8].Thus, the instrument comprises items that assess the learners' mastery of medical language and symbols, their knowledge of the healthcare system, and health-promoting behavior.Additionally, students need to demonstrate that they can read, understand, and appraise health-related texts, graphs, websites social media, and numerical information.Though the instrument is mainly a performance-based instrument, two smaller self-report parts inquire into students' motivation and self-efficacy toward health maintenance behaviors and their awareness of the importance of HL.

Item generation
We wanted our instrument to measure adolescents' knowledge and skills, which together constitute their competencies.We also desired the instrument to collect objective, not only self-report data since studies have shown that people can overrate their HL abilities [23] or tend to provide socially desirable answers.Moreover, we wanted the instrument to reflect the text-based approach to learning so typical of education in secondary schools, where students learn content through interaction with texts.
Two secondary school health sciences teachers, two teacher trainers in the area of health sciences, a research assistant, and the author of this article contributed to the development of the test items.The development was guided by an expert panel, consisting of a medical psychologist, two additional secondary school health sciences teachers, two experts in pedagogical sciences, and two research assistants who were not otherwise involved in the project but had researched the acquisition of HL before.Test items had to be developed with respect to the different dimensions of the concept definition of HL chosen as the theoretical foundation of the test.The endeavor was to work with as many closed-ended yes/no items as possible in order to make automatic corrections of the items possible.The items had to represent various levels of difficulty, covering easy, medium, and difficult content.The first assessment of the difficulty level was conducted by the item writers and the expert panel, and the final assessment, applying statistical tests, was based on the solution percentages of the items in the validation study.
In total 160 items were generated.Out of these, 92 items were chosen for the field test.They covered all dimensions of the conceptual framework and reflected the text-and media-based approach commonly used in secondary education.They tested functional literacy skills, including simple reading and numerical tasks, and more difficult ones, where students had to apply information and appraise it to be able to answer the question.The expert panel members had judged these items' construct validity, level of difficulty, appropriateness, and usefulness in an educational context.Also, a small test group of 12 adolescents (4 from general secondary education, 4 from technical secondary education and 4 from vocational secondary education) assessed the items' understandability and suggested 4 items to be reworded for greater clarity.

Feedback from test audience
The 92 items were offered to a small test group (N = 30), comprising 10 students from general, technical, and vocational education.All items that were found to be unclear, too complex, or too easy were removed from the test.Eighty-six items were retained for test validation.

The instrument and its construct validity
The questionnaire consists of 14 sections: 1. Self-report on general HL skills 2. self-report on media literacy skills and motivation 3. understand medical language 4. find information on a health website 5. understand a doctor's interview 6. understand symbols related to healthcare, the healthcare system 7. appraise online health information for reliability 8. correctly complete the nutrition triangle 9. name medical professions and identify the purpose for consultation (knowledge of the healthcare system) 10. interpret a patient package insert (apply the information) 11. answer questions about a nutrition label (apply the information) 12. interpret a health graph 13. interpret a table on recommended daily amounts of vitamins (apply the information) 14. a calculation task on health figures (apply the information) The first question uses the European HL Questionnaire (EHLQ) [24].That EHLQ considers HL with respect to three domains, namely healthcare, disease prevention, and health promotion.It defines HL in terms of knowing how to access information (access, find), understanding that information (comprehend), being able to assess that information (evaluate, appraise), and, finally, being able to apply it to promote one's own health.Using a 4-or 5-point scale, test takers are asked to indicate to what extent they believe they would find it easy or difficult to perform a particular healthcare, health prevention, or health promotion task.An example item is: How easy is it for you to find information about the health conditions you are dealing with?(answering options: cannot do or always difficult, usually difficult, sometimes difficult, usually easy, always easy).In total, test taker score 10 self-assessment items.
E-HL is the central concept in the next section of the questionnaire.This part of HL refers to the ability to read Internet sites, use computers to find information on the Internet, understand health-related information, put it in context, and apply it to the maintenance or improvement of one's own health.To assess the e-HL of adolescent pupils, the eHL Scale (eEHEALS) [25] is used as a model instrument.The eHEALS consists of eight items, of which we use four in order to avoid overlap with the items selected from the EHLQ.An example item is: I feel self-confident in using information from the Internet to make decisions about my health.All items have to be scored using a 4 point-scale, ranging from 'strongly agree' to 'do not agree at all' .
After these first two sections, which focus on the pupils' self-assessment of their HL, pupils are asked to perform HL-related tasks and demonstrate their knowledge and skills.The first task aims to assess the extent to which pupils understand medical language.For this question, inspiration was found in the Short Assessment of HL (SAHL), in the English [26], and Dutch version [27].In this test, the respondents first pronounce the word in the first column correctly and then circle which of the two words in the second or third column has a closer association with the word in the first column.To avoid guessing, the 'I don't know' option is also provided.In a school-based context where the HLQE is used in a written format, pupils would not be required to read the words out loud as a first check of their comprehension of the words.The majority of the words from the SAHL-E and SAHL-D were replaced by other words because they were either too easy or too difficult for adolescents, or too far removed from their world.In total, the test takers are asked to score 20 words.An example of a word from the first column is mammogram.Here, respondents had to choose between pregnant, breast or I don't know. 1 3 The next task wants to check whether pupils can effectively extract the correct information from a website.To that end, the test takers are given the menu from a medical website and have to indicate under which menu button they think they will find the answer to five different questions.

An example of a question is You suffer from hypertension and want to know what the possible cause of this is. Under which title do you think you can find information about your blood pressure?
This task has to be performed with respect to five such statements.
Next, the respondents are asked to take part in a written-out conversation with a general practitioner and indicate whether they understand what the doctor tells them.The GP makes seven statements.An example statement is: It is clear that you suffer from chronic bronchitis.The respondents then have to choose between the answering options long-term, severe, contagious or I don't know.
To chart whether adolescents can identify what medical symbols refer to, they are asked to write down what each of the twelve symbols in the questionnaire refer to.Symbols include a picture of a label indicating the nutritional value of a product, the sign for 'wash your hands after touching a dangerous product' , or a picture of lungs.
To investigate pupils' information literacy, they are asked to assess the reliability of three pieces of text taken from different sources.For example, they are shown a post on Facebook from Coffee and more, an article from the Libelle website-Libelle is a popular women's magazine -, and an article from a governmental medical website (www.gezondheidenwetenschap.be).For each piece of text, they have to rate its reliability on a scale from 1 (not at all reliable) to 5 (very reliable).They also have to explain in brief words why they pick a particular answer.To check whether respondents can also find reliable information themselves, they are asked to list four sources of reliable information in order of importance.
The completion of the next task consists in filling out the food triangle correctly.Pupils are given an empty food triangle as well as a series of food products which they have to sort and enter into the food triangle.This task wants to inquire into pupils' familiarity with this important visualized guideline for healthy food consumption.
Section 9 asks pupils to name four kinds of medical professionals and to identify the health-related problems with which they can turn to them for help.
The next series of tasks inquire into pupils' information literacy, reading ability, and numerical literacy.First, to investigate whether students understand general and detailed information in a written medical text, they are asked to answer six questions regarding part of a patient package insert.Sample questions include At what time of day is Depakine best taken?and What is the maximum amount of milligrams of this drug that a 60-kg adult should take per day for the treatment of epilepsy?The total number of questions here equals six.Secondly, pupils are given a nutrition label of a container of ice cream, much like in the NVS (Newest Vital Sign) test [28], and have to answer six questions, including If you are allowed 60 g of carbohydrates as a snack, how many servings of ice cream are you allowed to eat?.Furthermore, the respondents are asked to correctly interpret figures from a health-related graph.The graph concerns the total fertility rate in Flanders.Of the five questions test takers are presented with, one is Which group has the highest fertility rate?
The final two tasks are of a higher level of difficulty than the previous ones and aim to further determine the participants' health-related calculation skills.In task one, the pupils are given a table showing the recommended amount of vitamins per day.An example question is How many grams of iron should you consume daily to maintain good health?To answer this question, respondents not only have to know which chemical symbol stands for which chemical element.They also have to make a correct conversion from milligrams (as in the table) to grams (as in the questions).The very last task is an abbreviated version of the General Health Numeracy Test (GHNT) [29].The GHNT is an objective test to assess the health numeracy skills of test takers.

An example question is Your doctor tells you that you have high cholesterol. He informs you that you have a 10% risk of having a heart attack. If you start taking a cholesterol-lowering drug, you can reduce your risk by 20%. What is your risk of getting a heart attack if you take the drug?
As can be seen from Table 1, the HLQE has a firm conceptual basis and covers all important aspects of Baker [10] and Bröder et al. [22]'s definitions of HL.

Validation study
132 18-year-old students (convenience sample) participated in the validation study, with one-third taking classes in general secondary education, one-third in technical vocational education, and one-third in vocational secondary education.The study was approved by the KU Leuven Privacy and Ethics Committee (PRET).All participants filled out a written informed consent form together with their parents, and the methods used in the study were carried out in accordance with relevant privacy guidelines and regulations.Test administration took on average 35 min, with some students in vocational secondary education needing about 50 min to complete the pen-and-paper test.

The instrument and its construct validity: factor analysis
For the Factor Analysis, varimax rotation was chosen so as to be able to highlight a small number of important variables, which makes it easier to interpret the results.The results of the principal component analysis, from which the two selfreport sections of the questionnaire have been removed as they do not show actual performance, show that underlying the performance-based instrument are two distinct factors, which we have identified as 'knowledge' component' (factor 2) and 'skills' component' (factor 1).These factors meet the instrument's underlying construct as shown in Table 1.The internal consistency of the two factors is Cornbach's alpha = 0.894 (Factor 1) and Cronbach's alpha = 0.784 (Factor 2).

The difficulty of the instrument's subsections
The mean solution percentages, ranging between 40 and 81%, show that the test items are of different levels of difficulty as was intended by the test developers.The level of difficulty is the percentage of students taking the test who answered the items correctly (Table 2).The larger the percentage getting an item right, the easier the item is understood to be.The results show that respondents mainly found the exercises that required calculation the most difficult.For instance, respondents scored lowest on the exercise on health figure (scores out of 100) (M = 50.41,SD = 24.18)and the exercise on  vitamins (M = 43.75,SD = 29.44) in which they had to know which chemical symbol stands for which chemical element and in which they also had to do a correct conversion from milligram to gram.Similarly, the exercise in which respondents had to extract the correct information from a package leaflet also proved difficult for quite a few students (M = 58.69,SD = 27.90).Respondents scored better on the exercise on medical language (M = 61.29,SD = 17.95) and the exercise where they had to fill in the nutrition triangle correctly (M = 62.34,SD = 16.23).To interpret a health graph (M = 77.03,SD = 30.66)and a nutrition chart (M = 71.99,SD = 29.32)went more smoothly for most students than the arithmetic exercises.Respondents scored highest on the exercise in which they had to find the correct name under a symbol or drawing in a medical context (M = 83.92,SD = 29.71)and the exercise in which they had to circle the correct meaning of certain words during a doctor's conversation (M = 86.24,SD = 16.89).
The test scores also show substantial differences between students in general, technical and vocational education, as can be seen from Table 3.The mean test score for pupils in general secondary education is 76,4%, for pupils in technical secondary education 69% and for students in vocational secondary education 41,9%.These findings reflect our expectation that students from aso (general secondary education) would score better than students from tso (technical secondary education) and bso (vocational secondary education), and also that students from tso would do better than students from bso.The food triangle section and the health graph section appear to have least discriminatory power.An analysis of the items that were part of the medical languages subtest showed that one of the twenty items was not discriminatory because it was too easy (hormones), and five were not discriminatory because they were too difficult, i.e. unknown to almost all pupils.They are: ECG, pneumonia, bipolar, mammogram, saturation meter.These words have been replaced in the final test version.
A one-way ANOVA showed that the mean test scores differ between groups for all test parts.This is the case for the medical language test (F(2, 129) = 16.52,p < 0.05), the medical symbols test F( 2

The instrument's reliability
The reliability, as measured by Cronbach's alpha coefficient (Table 4), was calculated to measure the internal consistency of the items belonging to the performance-based part of the HL scale, bearing in mind that the alpha coefficient indicates how closely related a set of test items are as a group.The Cronbach's alpha (0.874) coefficient shows a strong internal consistency of the instrument.

Discussion
The overall aim of the study reported here was to develop a construct valid HL assessment instrument for use in an educational context.Construct validity as well as item clarity and comprehensibility were established by an expert panel, and a group of adolescents representative of the study sample.Together, the task and skills-based performance tasks included in the instrument provide a multifactorial picture of students' HL.The instrument is reliable and internally consistent.It is also able to distinguish weaker from stronger students.Some tasks, especially the calculation tasks, appear more difficult for students.Distinguishing healthy from less healthy foods, or understanding medical language appears more easy.Recognizing medical symbols as well as vocabulary in a doctor's conversation appears easiest.This is true for the three student groups, namely students studying in general, technical, and vocational secondary education.Even if the test takes longer to administer than, for example, the HLAT-8 test (Guo et al. 2018), the information gained from our test can build the direct starting point for developing an HL curriculum that can meet the test takers where they are.When tasks still appear difficult to master, additional tasks of the same type can be set for students to help them deepen their mastery of the targeted HL skill.This repetition of tasks will lead to the sharpening of HL skills as students need to apply them in forever new situations with respect to forever new health-or disease-related information.
When studying the results of the test in terms of students' HL, one important implication of the study indeed is that more efforts need to go into preparing students for adult life in which they will need to function autonomously in the domain of health prevention, health care, and health promotion.The study demonstrates that, in particular students from vocational secondary education, lack the knowledge and competencies to complete functional, interactive, or critical health-related tasks well.They understand less than half of the medical language, are next to unable to read and understand a patient package insert or a food label and perform badly at calculation tasks.
Educational efforts may target the said tasks in the first place, but will in general need to put the promotion of HL higher on the literacy education agenda.Some rediscovery of the importance of health education is needed, together with a sufficient widening of content and the methods used [6].To do so, investment in teacher education is necessary as many teachers who are now required to also teach HL lack confidence and need ongoing professional development.Pursuing the goal of improved HL will also require more overt alliances between the health and education sectors.
Several limitations should be noted.First, convenience sampling as used in this study may limit the generalizability of the findings.Our sample was recruited from four secondary schools in Flanders.Being Dutch-medium schools with lower percentages of non-Dutch-mother tongue speakers, the results may be higher than they would be in schools with larger percentages of non-Dutch speakers.This realization is unfortunate given the already low level of HL observed for students in vocational secondary education.Secondly, future studies will have to prove whether the instrument that was developed within one particular context has a more general bearing and can be used within other (educational) cultures that are perhaps less skills-and more knowledge-oriented.Thirdly, the study did not use a test-retest design, nor did it investigate the existence of a correlation between existing HL measurement instruments for use with English-speaking adolescents in an educational context.Even if the present study did not focus on the comparison of different instruments, also because it is difficult to compare self-report and performance-based instruments, the comparability of students' performance on different test types needs to be explored in future research.To that end, translations of these instruments into Dutch would need to be developed via a forward and translate-back method [15].Fourth, as proposed by Fleary [11], Rasch statistics could be used in the future to study the trade-off between the respondents' abilities, and the item difficulty.Also, to fully establish the instrument's construct validity, a successful confirmatory factor analysis needs to be conducted, which would require the use of a larger sample.Fifth, longitudinal designs should also be employed in the future to study to what extent the task types used in the current measure remain fit for measuring adolescents' HL and can distinguish between weaker and stronger student groups.Sixth, future research will need to take into account future developments in the concept of HL [6] as well as common information retrieval strategies used by respondents (e.g., online searching).The content and mode of delivery of health education have to continue to evolve to reflect these changes, to enable adolescents to navigate competing sources of information.Seventh, it will also be important that the effectiveness of different approaches to HL teaching are compared in experimental studies set up in educational settings.Finally, it is equally important that the specific role of education in HL promotion be clarified further within the wider context of health promotion by the medical sector or governmental organizations and institutions, such as the WHO, CDC, or locally based agencies.

Conclusion
We have developed and validated a theoretically grounded competencies-based multidimensional HL measurement instrument for use in secondary education.The instrument constitutes a very valuable addition to the field of measuring HL in adolescent education.It is our hope that the instrument will be widely used and will yield evidence on which educational authorities can build when designing curricula for promoting the HL of young people, given the importance of HL for individuals and for society as a whole.