Once addition has been explored a bit, it leads pretty naturally to a new question: if there are three bricks in a pile, how many bricks do I need to add to it so that there will be five in the pile?
Our addition problems were all phrased using a pattern like
number + number = what?
and the question above rearranges it a bit:
number + what? = number
what? + number = number
This question is usually asked as “What is the difference between Continue reading Algebra Intro 3: Subtraction