section_path: In formal education/Documents for teachers
section_name: Documents for teachers
paragraph_text: Documents for teachers
  
  Several states in the United States have adopted learning trajectories from the Common Core State Standards Initiative 's guidelines for mathematics education. Aside from sequencing the learning of fractions and operations with fractions, the document provides the following definition of a fraction: "A number expressible in the form a {\displaystyle a} / b {\displaystyle b} where a {\displaystyle a} is a whole number and b {\displaystyle b} is a positive whole number. (The word fraction in these standards always refers to a non-negative number.)" The document itself also refers to negative fractions.