According to my research on different types of research strategies, I can say that based on the information provided within the question Dr. Martin used a longitudinal approach. This strategy focuses on repeatedly observing a specific aspect or variable over a short or long period of time in different intervals. Which is what Dr. Martin is doing by testing the same group of children with the same test 2 years apart.
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Health, population and environment education is introduced as an integrated subject due to profound interrelationship that exists among the subject matters of these three disciplines. The natural physical aspects and man- made things come under the physical aspect.
