Study design and setting
The present pre–post intervention study with a two-stage (schools and classrooms) cluster sampling was conducted on 1781 students studying in 8th to 12th grades between July 2018 and December 2018. The study was conducted in Ujjain district, Madhya Pradesh, Central India. Ujjain district has 5 sub-districts, covering 6091 square km, and is a plateau [17]. The district has a population of approximately 2 million (1986864); approximately 61% (616353) of the population resides in rural areas, with mostly an agrarian economy [17].
Sample size calculation
To calculate the sample size, a pilot study was conducted on 65 students, in which the students answered 54% of the questions correctly. Sample size calculation was performed with one sample comparison of proportion 54%, two-sided alpha of 0.05, and power of 90%. The minimum sample size obtained after calculation was 1613, to which 10% was added to account for attrition or refusal rate. Thus, the estimated sample size was 1774. The students who participated in the pilot study were not included in the main study.
Sampling strategy and data collection
A list of public and private higher secondary schools (grades 8th to 12th) along with number of students in each class was obtained from the District Education Officer. In the first sampling stage, public and private schools were selected randomly from two separate lists of all the public and private schools. Figure 1 illustrates the sampling procedure and the inclusion and exclusion criteria for the selection of schools. Of the 514 public and private higher secondary schools in the Ujjain district, 72 schools having a strength of at least 40–50 students in each class of 8th–12th grade were selected to reduce the number of visits required to obtain the estimated sample size. Among the selected schools, 12 schools from rural area and 12 schools from urban area were selected randomly by using computer-generated random numbers.
To collect data, a structured WASH-knowledge questionnaire was developed in English, which was then translated to Hindi according to the WHO recommendations for questionnaire translation [18]. The WASH-knowledge questionnaire comprised 15 questions, which were divided into 4 sections: water (1 question), sanitation (5 questions), hygiene (3 questions), and knowledge about diarrhea (6 questions on definition, causes, signs and symptoms, and community treatment). (Additional file 1-questionnaire in English).
The questionnaire also included limited demographic information such as name, age, class, and gender of the participating students. Each test was completed in approximately 20 min. Each correct answer was given a score of 1. Some questions had multiple correct options. The minimum and maximum possible scores were 0 and 44, respectively. The same questionnaire was used after educational intervention to assess the effect of the intervention. The distribution and collection of the questionnaires was facilitated by 4–6 trained research assistants, who were present in class during the session. They helped the students to understand the questions in case of any difficulty; however, they did not help the students in answering the question.
Educational intervention
A visit was scheduled for each school before starting the intervention. Informed consent was obtained from both the school principal and students. The team of trained research assistants asked the students to fill-in the structured WASH-knowledge questionnaire. The team ensured that the questionnaires have been completely filled by the students; in case of any missing information, they interviewed the students and filled the missing detail. The principal researcher visited the schools to supervise the survey activities. No efforts were made to contact the students who were absent on the day of data collection.
The educational intervention consisted of an approximately 60-min practical training session, which included a training module in the form of a flip chart with appropriate diagrams and pictures to convey the WASH-related messages to the students, shown in the classroom as power point presentation. The training module was based on the “Save The Children” community intervention module for childhood diarrhea [19]. Examples of some of the figures used in the educational intervention are depicted in Additional file 2.
Two class periods (90 min) were used to complete the 20-min pre-intervention questionnaire, and the 60-min intervention was provided on the same day. The students were not informed about the post-intervention questionnaire. After the intervention, the students were asked to complete the same WASH-knowledge questionnaire in 20 min after a minimum gap of one month. Overall, 144 sessions were conducted in 6 months, which included 72 pre-intervention and 72 post-intervention sessions.
Fidelity of intervention
To maintain fidelity in implementation of the intervention, the research assistants received training by the principal investigator. A 4-h training session was conducted to explain the intervention module. All slides in the power point presentation, pictures, and videos were discussed with regards to content and the method of delivering the content. The concepts were reinforced by providing the research assistants an opportunity to engage in role-playing. The training session was repeated once every fortnight during the study period. A training manual was used to articulate the content and delivery of the educational practical session.
Ethical considerations
The Institutional Ethics Committee of R D Gardi Medical College, Ujjain, India approved the research protocol (IEC-RDGMC-493). Prior permission was taken from District Magistrate, Ujjain to approach the schools and to intervene. Consent to participate in the study was obtained from parents of the students, and assent was obtained from the students. All the students present on the day of data collection were asked to participate.
Data management and analysis
Data was collected in schools through paper-based questionnaires which were later entered in Epi InfoTM (Version 7.2). Data analysis was done using Stata (Version 16.1, Stata Corp, College Station, Texas, USA). Descriptive statistics were used to determine the proportion of correctly answered questions by the students in the pre and post-intervention. Pearson χ2 was used to test the significance of the difference in proportions in pre and post intervention. For continuous variables, range, mean and standard deviation was presented. Means of pre and post-test scores were compared using repeated measures analysis of variance (ANOVA). The effect size of intervention was determined by calculating Cohen’s d. Multivariate quantile regression models were used to test the association between difference in pre and post-intervention score (outcome) and independent variables. The independent variables included Quantile regression model was chosen to capture the full distribution of the outcome- difference in pre and post-intervention score. The coefficient (b), and 95% confidence interval was estimated for 10th, 25th, 50th (median), 75th and 90th quantiles of the difference in pre and post-intervention score based on 500 bootstrap samples. The multivariate quantile regression analysis was performed using the simultaneous quantile regression command in Stata (Version 16.1, Stata Corp, College Station, Texas, USA). A P value <0.05 was considered significant.