In a survey conducted with children living in the Nordic countries (Norway, Denmark, Finland, Iceland and Sweden) based on how often they were engaged in physical activities, and where a total of 4958 children between the ages of 7 and 12 participated in the study, showed that only 40% of the children who participated in the survey were physically active each week. And more boys than girls achieved the recommendation of physical activity, the recommendation meaning that children should engage in some light pulse-raising activity at least four times a week, and with at least 30 minutes of moderately intense activity. The highest percentage of children who did not achieve recommended physical activity, was observed in Sweden, where 60% of children did not achieve the requirements. At the same time, relatively new research has been emphasizing that few things are as important for the brain as that we should daily be engaged in some kind of physical activity. Thus, being physically active not only makes you feel better, but it also affects concentration and memory positively. This can lead to that processing information is faster and students are predicted to become better at mobilizing mental resources when needed. Thus, students in a classroom climate where concentration is needed, even where noise can occur,.can get an extra gear to be able to engage when things are messy around and when focus is needed on a task.

The purpose of this study was to investigate whether 30 minutes of physical activity can affect students' performance in primary school in biology concepts. The study was performed in a primary school in central Sweden. The method was to test if there were any effects on whether 15 minutes of walking and 15 minutes of light pulse-raising activity could affect students' performance in a subject in biology for grades 1-3. The study rests on neuroscientific grounding based on how physical activity can affect cognitive functions in students. The method is based on a comparison between two student groups where one group participated in physical activity and the other group completed 15 minutes of film and 15 minutes of reading. A pre-test was performed in both control and experimental group before any teaching began. Five teaching lessons on biology concepts of natural history of animals and trees were performed over the course of about three weeks, and each lesson was conducted directly after the experimental group had been out for physical activity.

The post-test was performed about a week after the last lesson was done. Based on both pre- and post-tests between the teaching trials, data were created to measure differences in performance between the groups. The post-test showed a significant increase in the performance of both the control and the experimental groups compared to their pre-test. Thus, there was a significant increase from pre-test to post-test in both groups, and interestingly there was a significantly greater increase in the experimental group compared to the control group (F = 31.24, p < 0.0001). Thus, the result of our study shows that physical activity leads to significant improvements in the students' school performance. The conclusion that can be drawn from this study, is that regular physical activity not only improves the students' physical health, but also their cognitive abilities. This study strengthens the argument for integrating physical activity into the school's everyday routines.

Keywords: Physical activity, cognition, Nordic countries, experiment.