Studies Conducted at Elementary Schools Have Shown That Children with Longer

Short Answer

Studies conducted at elementary schools have shown that children with longer feet tend to score higher on reading tests than children with shorter feet.
a. Are these studies observational or experimental? Explain briefly.
b. Suggest a potential confounding variable that could explain the observed phenomenon that children with longer feet tend to score higher on reading tests than children with shorter feet. Describe what makes this a confounding variable.