A complete unit with direct instruction to the student, ample practice problems, and word problems. Common Core aligned. Great for independent practice/homework!
The unit Strategies for Addition & Subtraction Facts Within 18 deals with two main themes:
- MENTAL MATH STRATEGIES FOR ADDING AND SUBTRACTING WITHIN 0-20; such as adding just one more, a trick with nine and eight, and subtracting using addition;
- MEMORIZING THE BASIC ADDITION AND SUBTRACTION FACTS of single-digit numbers.
In the first several lessons we study basic strategies for adding and subtracting within 0-20, such as adding one more; a “trick” for adding 9 or 8; subtracting to 10; and subtracting using addition.
After those, we study the idea of completing ten and going over. For example, the child adds 8 + 5 by first adding 8 + 2 (which makes 10), and then adding the 3 that was “left over”. All of these lessons in the beginning part prepare the student for the next part of the unit, which has to do with memorizing the basic addition facts.
The next lessons in the unit (Adding with 9, Adding with 8, Adding with 7, and Adding with 6), provide lots of practice for learning and memorizing the basic addition facts. There are 20 such facts:
from 9 + 2 to 9 + 9: 8 facts (lesson Adding with 9)
from 8 + 3 to 8 + 8: 6 facts (lesson Adding with 8)
from 7 + 4 to 7 + 7: 4 facts (lesson Adding with 7)
from 6 + 5 to 6 + 6: 2 facts (lesson Adding with 6)
Some children will accomplish this more quickly and need less practice. Some will need more practice. You can also add in games (a list of internet-based online games is provided in the book).
Learning and memorizing the basic addition and subtraction facts of single-digit numbers is very important for later study. For example, regrouping (carrying/borrowing) in addition and in subtraction requires that the student is able to recall all the sums of single-digit numbers and corresponding subtraction facts efficiently and fluently. The goal is to memorize these facts, or at least become so fluent with them that an outsider cannot tell if the student remembers the answer or uses some mental math strategy to get the answer.
I wish you success with math teaching!
Maria Miller, the author