The Seattle Times – John Higgins
“On the road to algebra, children must learn a weird idea: that numbers can be smaller than zero (negative) and can be mixed with numbers greater than zero (positive) in an equation. Now researchers at Stanford University have created a hands-on way for students to grasp the concept, which appears to harness the brain’s natural ability to notice symmetry in the world. They found that when they directed fourth graders’ attention to the symmetry between negative and positive numbers (that -5 is the same distance from zero on a number line as + 5, for example), the students got better at solving the problems. And they were able to apply that insight to new problems such as figuring out where to locate positive and negative fractions on a number line.”(more)