Hope everyone is having a great March Break. For those of you interested in working on some math...
Addition and Subtraction Skills (this unit):
Estimation - round numbers to estimate sums and differences. Why is it important to estimate? Estimation is a good way to check if your sum or difference is REASONABLE (it makes sense).
Adding - There are many ways to add. We looked at two ALGORITHMS. For example...

Subtracting - You can use an algorithm

You can add up using a number line

 You could also make an easier question by adding or subtracting the same amount to both numbers
12 000  (-1)   11 999
- 5479   (-1)    -5478

When you subtract 1 from both numbers the subtraction is easier because there is no regrouping.

Grade 4 are expected to add and subtract four-digit numbers, grade 5 five-digit numbers using a VARIETY of strategies. You may prefer one strategy over another and that's okay. But make sure you are able to arrive at the same answer using a different strategy. It's a good way to check your answer, not just if it is reasonable.

Solving Addition and Subtraction Problems:
The most important skill is knowing when to add and when to subtract.
Adding to solve a problem usually is about find the total or combining two amounts.
Use subtraction to solve a problem if you have to:

• Find out what is left 
• Compare two numbers
• How much more is needed to get to a number

Some problems you have to use BOTH addition and subtraction (2 -Step).

One strategy we used is using a model when you know the sum of two numbers and difference, but not the actual two numbers.

For example:

6760 books were checked out of the library on Friday and Saturday. 800 more books were checked out on Saturday. How many books were checked out on each day?

6760
3380 (half of 6760)		3380 (half of 6760)
3380 – 400 (half of 800)	3380 + 400 (half of 800)
2980	3780
3780 books were checked out on Saturday and 2980 were checked out on Friday.

Check:

            3780               3780

         +2980              -2980

            6760                800

Try to figure out this grid:

Creating Addition and Subtraction Problems:
What subtraction problem could you make using the following information:

Create a word problem that involves adding two 4-digit numbers and getting an answer of 5000.
Make up two different word problems that involve using 2000 - 1200 to get the answer.

Reminders:

• Don't forget to work on your Mathletics assignments!
• Practice your multiplication facts

http://www.multiplication.com/games/all-games