Reviewing Subtraction Facts and Fact Learning Strategies

Fact Learning – Subtraction


At the beginning of Grade 4, it is important to ensure that students
review the subtraction facts to 18 and the related fact learning
strategies. All subtraction facts can be completed using a “think addition”
strategy, especially by students who know their addition facts very well.
In addition, there are other thinking strategies that will help students
master the subtraction facts.
All subtraction facts can be completed using a “think addition”
strategy, especially by students who know their addition facts very
well.
• Up Through 10:
This strategy involves counting the difference between the two numbers
by starting with the smaller number, keeping track of the distance to ten,
and then adding this amount to the rest of the distance to the greater
number.
Examples
a) For 12 – 7, think, “Starting at 7, it’s 3 to get to 10 and then 2 more to
get to 12, so that’s 5 altogether”
b) For 16 – 9, think, “It’s 1 from 9 to get to 10, and then 6 more to 16, so
that’s 7 altogether”
 • Back Down Through 10:
With this strategy, you start with the larger number and subtract part of
the subtrahend to get to 10, and then subtract the rest of the
subtrahend.
Examples
a) For 15 – 8, think,“15 subtract 5 (one part of the 8) gets me to 10, and
then 3 more (the rest of the 8) takes me to 7.”
b) For 13 – 4, think, “13 subtract 3 is 10, and then 1 more takes me to 9”