WEEK TWO: Subtraction
- Cassie-Jaye Simmons
- Mar 8, 2016
- 3 min read
WHAT IS SUBTRACTION?
(Week Two Lecture)
(Week Two Lecture)
Subtraction Concept: Cover mats can be used to help children explore and understand the concept of subtraction
(Week Two Lecture)
Subtraction Strategies:
(Week Two Lecture)
In tutorials this week we:
- Used concrete manipulatives (MAB) and mathamatical language in unison with symbolic language, to help create visual representation of subtraction, place value and trading (NOT borrowing! Afterall, we dont give it back, do we?)
- We looked at subtraction books (concrete/visual) that explore subtraction in student language.
With this book as example, and in particular the second image above (a page from 'A Week Away'), you could ask the children a missing addend question:
Teaching Strategy - Using books, as pictured above, teachers are using visual/concrete aids to teach addition. This idea could be introduced slowly, with students simply doing an activity on listing the days of the week and what the squirrels did on that day. Then, with the idea of subtraction being introduced, students can use their prior activity to do some subtractions. An example from the book above - " If Tuesday is the second day of the week, how many days do they have left camping if they go home Sunday?" - The students could use the count back strategy, to count back from Sunday to Tuesday and tally the days.
Unit Learning Resource:
(Retrieved from Week 2: Learning Activities)
Language Model:
Misconception: That subtraction is taking away to find the total - But, dont we already have the total?
How to change this misconception: Use a large pile of tokens to represents a total value (concrete/visual), to help students visualise that we do already have the total. You could possibly have the children in groups, and ask each group a different question. For example, "The diamond group, you have 15 tokens, correct? If you wanted to share those tokens equally between 5 friends, how many would each friend have". In doing this the students can re-enact the question.
Further Resources:
Fact family Worksheets - These could be laminated, and filled in using whiteboard markers during morning rotational activities.
(Rainbow Resource Centre. (n.d.). Fact Family [Digital image]. Retrieved from http://www.rainbowresource.com)
- A concrete/visual youtube clip that introduces children to subtraction in student language, whilst also visually linking the story to the recording of symbolic language.
(Smart Learning For All. (2015, June 20). Basic subtraction for kids [Video file]. Retreived from https://www.youtube.com/watch?v=depLStKzbIE)
A visual poster in student language which may assist children in remembering the order of workings.
(I'm Blog Hopping. (2013). Subtraction strategies [Photograph]. Retrieved from http://imbloghoppin.blogspot.com.au)
How has my understanding on Subtraction changed?
Borrowing Vs Trading - Going though primary school in the mid 90's, I can not recall being visually shown the concept of trading. We were taught to "just borrow from over here". It is like a lightbulb moment (as an adult learner), when it is actually shown to you, and all of a sudden it all makes perfect sense! I enjoyed doing the fact family activities, and I feel it will be a great resource in my teaching career, as it really helped me connect the idea that subtraction is the inverse of addition. Seeing the important connection that addition plays in subtraction and other operations, I will always endeavour to create meaningful learning experiences so students grasp all concepts in their entirety.
ACARA Links to Subtraction in Year One
http://www.australiancurriculum.edu.au/mathematics/curriculum/f-10?y=1&s=NA&layout=1
(Australian Curriculum, n.d.)
Scootle Resource:
- The below resource is a video that visualises the concept of subtraction, as a Captain counts out his crews wages. This video is great as it uses student language to help introduce the 'take away' concept of subtraction.
(http://splash.abc.net.au/home#!/media/522497/)
Idea Summaries from Textbook:
Chapter 2: Helping children learn mathematics with understanding
Chapter 9: Operations meanings and basic facts - subtraction
- Subtraction: Seperating, comparison, part-whole
- Thinking strategies for subtraction - (Reverse addition): Subtracting 1 &2, Doubles, counting back, counting on.
Chapter 11: Solving mathematical problems with standard and alternative written strategies - subtraction
- Learning strategies that lead to understanding include the use of manipulatives and using place value
- Decompossing algorithm (standard) - Logic process of decomposing the sum.
- Partial-difference algorithm (alternative) - Subtraction the hundred, then the tens, then the ones.
(Reys, Lindquist, Lambdin, Smith, Rogers, Falle, Frid & Bennett, 2012)
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