Everyday language   Another way of teaching addition and subtraction, is through situations from everyday life, which are described by texts in everyday language. This method raises problems of multiple meanings of many words this in addition to the other drawbacks of using the groups (9). For example: The expression "the balloons popped" can be related to a situation of subtraction in the following context: "Danny had 5 balloons, and 2 of them popped. How many balloons did he have left?" But the same expression can be related to a situation of addition in the following context: 5 of Danny's balloons popped in the morning, and 2 popped in the afternoon. How many of Danny's balloons popped? The use of rods for teaching addition and subtraction enables to bypass, at this stage, coping with the problems of multiple meanings in the spoken language. The expressions we use - "an addition exercise", "a subtraction exercise", and "the three rod configuration" - derive their meaning from operational definitions, which are simple and have one single meaning. This way we need no verbal descriptions, which have multiple meanings and can be interpreted in different ways. For example: We make sure to use a single instruction for the addition operation in rods: "place the two rods in a straight line, edge to edge." We don't use an instruction which can have multiple meanings, like "place the two rods together", since it can be interpreted in different ways. Coping with texts of everyday language, which have situations of addition and subtraction, will take place at a later stage, in the chapter dealing with word problems, after the students know and understand the essence of addition and subtraction, and know the number facts.