But for most kids,labels applied early in life tend to stick,even if they are wrong. Sorting school children by ability has long been controversial.In some countries,especially in Asia,school-wide tracking  remains normal.Children are tested and placed in different schools that direct them toward professional or vocational careers.Movement between the tracks is rare. School-wide tracking decreased in U.S.schools in the 1960s and 1970s.It never died out,though.Sorting students into separate tracks for math at about junior high school age continues to be common,and other forms of tracking persist as well. Unlike tracking,which means sorting students into separate classrooms,ability grouping happens within classrooms.When done according to the latest research,it has proven to promote achievement. Ability grouping is changeable and temporary.Within classrooms,students might be divided into different learning groups dealing with materials of different levels.Any students who master concepts can move upward between groups,and the student groups might look different from subject to subject and unit to unit.For instance,a student who stands out in language arts might be at an average or slower level in math.A student who flies through multiplication tables might need extra help with fractions.Students who lag in reading can be pulled out of the classroom in small groups for practice with a tutor until their reading improves. Research shows ability grouping within classes has more positive benefits than tracking.However,that must be weighed against the challenges involved.In many regular classrooms,the differences between student ability levels are very big.That presents challenges for teachers and low-performing students to constantly compare themselves with students who seem to fly through school with ease. The rigid ability groups and tracking of the past are still with us in many schools.Likely,labels are applied with more caution than in the bad old days when some teachers gave reading groups not-so-secret code names like"Bluebirds""Robins""Crows"and"Buzzards".But kids still know. Why is grouping children by ability becoming popular again?
Because most teachers do not like slower learners. Because grouping children should be done early in life. Because it is academically beneficial to different learners. Because fast learners can move ahead without teachers'help.