A recent article claims that "Green spaces make kids smarter". The study described in the article involved 2,623 schoolchildren in Barcelona. The researchers measured the amount of greenery around the children's schools, and then measured the children's working memories and attention spans. The children who had more vegetation around their schools did better on the memory and attention tests.

1. Is this study set up to be an experiment or an observational study? Explain.
2. If this study is an experiment, is it possible for this study to instead be an observational study? Explain. OR If this study is an observational study, is it possible for this study to instead be an experiment? Explain.
3. Suggestion one possible confounding variable.