In algebra, letters are used to stand for values that can change (variables) or for values that are not known (unknowns). A term is a number or letter on its own, or numbers and letters multiplied ...

The American Journal of Psychology, Vol. 107, No. 3 (Autumn, 1994), pp. 423-439 (17 pages) Students in 11th grade (N = 208) were assessed twice on the solution of algebraic word problems that ...