Subtraction Term Two 2012

Over the last few weeks we have been exploring strategies to help us solve problems involving subtraction.  We have discovered some generalisations about subtraction and some strategies that help us work out facts more quickly:

  • Subtracting 0 from a number gets the same number.
  • Subtracting 1 from a number gets the number that is one less.
  • Subtracting the same number gets 0. 4-4=0; 6-6=0; etc.
  • “Think Addition” – what number can you add to the number you are subtracting to get the starting number. For example, 9-4=__. What number can you add to 4 to get 9.
  • When subtracting 9, think subtract 10 and then add one on
  • Count backwards. We have a number line in the back of the room or students can make their own on their paper. For the problem 13-5=___, start on 13 and count back 5.

We have also used a number chart to help count back bigger numbers.  Some students have explored using an empty number line and this week we are going to try using a strategy called partitioning.

What strategy do you like to help solve subtraction equations?

Here are some websites that can help you practice getting quicker at recalling subtraction facts:

http://oswego.org/ocsd-web/games/mathmagician/mathssub.html

http://www.arcademicskillbuilders.com/games/sailboat-subtraction/sailboat-subtraction.html

3 thoughts on “Subtraction Term Two 2012

  1. When taking the time to look at my daughter’s blog (Mia.S.Prep W), I also enjoy looking at my nephew’s blog. I really enjoy being able to tap into what is being taught in Grade 2 and the information provided. For example, the above information about strategies used to solve subtraction equations is so very useful to us as parents. It provides continuity between school and home and helps us as parents (and Aunty’s) to support our children with the activities that we do with them at home! Thanks for sharing.

  2. Dear 2M,
    I love the Greater Than and Less Than symbols! It was really fun and enjoyable. i am Yacinta’s older cousin Kristen and Yacinta and I went through the great and less than progress. i loved going through it with her and ciney loved it to.
    From Yacinta and her cousin Kristen

    P.S, this is yacinta now:)
    I loved the greater than and less than symbols. I really like it. Thankyou for teaching me and the rest of the class about Greater than and Less than.
    Love from Yacinta

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