Thursday, June 13, 2013
Subtraction (Negative) Snake Game
Me Too has been working on the subtraction snake game (occasionally called negative snake game, but should not be confused with the ELEMENTARY negative snake game) this week. He thinks it is really silly that the snake shrinks.
I found presentations for this work in my Montessori by Hand Primary album and in my Montessori Research and Development lower elementary math album. However, this is one of those situations where a video is much easier to understand. I watched a video over at Montessori Live and am following most of their presentation format.
What I like about the Montessori Live presentation is that you don't count with a tab to find ten. You pull forward two or more bead bars at a time to create an equation. If the child has been using the colored bead bars since they learned teens and tens and through the chains work they will be very quick at identifying quantity by color. In this way they use their addition math facts to do practical work. At this stage we are counting backward one bead at a time when we reach a grey bar to do the subtraction or overlapping the negative bead bar onto the addend bars. When we play this game again at the end of the subtraction memorization sequence Me Too will be able to do that step without counting backward.
Note: This post was slightly edited to clarify terminology.