Using skittles or any small manipulative, create algabraic equations with a missing number - the X. (as in 2+X=5). Have the children construct the equation using the skittles on a piece of paper. The plus sign and equal sign should be drawn. Explain to the students how you must 'solve for the X' by maintaining the equality of each side. For example, if you subtract 2 from the left side to leave the X alone, you must also subtract 2 from the right side so that each side remains equal. By moving the skittles or manipulatives, the students will get a real feel for what is happening with the numbers.