April 11, 2008
I introduce algebra to my first graders with an 'In and Out' machine, which they love using. Draw a box like machine with an 'in' hole and an 'out' spout or shoot. Set up some examples of 'In' numbers with paired 'Out' numbers, like 'In goes 1, out comes 3. In goes 5, out comes 7.' (Rule is 'in'+ 2.) Kids have to figure out the rule of what is happening to the numbers in the machine. When they understand the concept, they can work as partners to make up rules and give the in and out numbers to each other. Later, talk about the 'in' number as 'n' to get them thinking about variables.