Addition and Subtraction

For the next while, we'll be working on operations, starting with addition and subtraction. This will encompass practising facts, mental math strategies, standard algorithms and solving problems.

The grade 5's need to:

-use knowledge of numbers and operations to solve mathematical problems encountered in everyday life 

-use the properties of operations, and the relationships between operations, to solve problems involving whole numbers and decimal numbers, including those requiring more than one operation, and check calculations (limited to addition and subtraction)

-represent and solve problems involving the addition and subtraction of whole numbers that add up to no more than 100 000, and of decimal numbers up to hundredths, using appropriate tools, strategies, and algorithms

-demonstrate the knowledge and skills needed to make informed financial decisions

-estimate and calculate the cost of transactions involving multiple items priced in dollars, using various strategies

Mental Math

Below are a few addition and subtraction strategies we will look at to replace the algorithm.  The idea is that students can do these steps in their head or even using paper and pencil.  In some instances, these strategies would be quicker than an algorithm.

Addition Strategies:

A quick and easy strategy that is used most often.
Move part of the value to the other number to make something friendly.

Round numbers to friendly values. Any added or subtracted amounts are accounted for at the end.

Start with the larger number, and add the smaller number in manageable chunks.

Subtraction Strategies:

Make a friendly number to take away from the bigger value;
whatever you add or subtract to make the number friendly must be done to the
 other number to maintain the range between the values.

Start with the large number, and take of the smaller number in manageable parts.

This strategy is helpful with money.
Start with the smaller number and count up until you reach the larger number.
The "jumps" or amount it took to reach the larger number is the difference.

Number Facts

We will rehearse number facts in class.  In order to commit these facts to memory, I recommend daily drills at home.  You can use Reflex, flash cards, xtramath.org or another tool you find useful.

There are missions posted on knowledgehook that can be accessed at home for further practice.