Happy Weekend!
Tubing was a huge success. Lots of laughter and enjoyment of the outdoors. The weather was wonderful and congratulations on representing St. Nicholas positively. BRAVO!
Math
Many students are still having difficulty with basic addition and subtraction with regrouping. We will have another short test on the skills on Wednesday. Tests will be given back on Monday for studying. Let's take a closer look at each strategy / skill.
Addition:
1. Adding using the standard algorithm / regrouping
Of all the skills this one was done the best. In order to apply this strategy effectively you must start at the place with the least value and move left, regrouping when there is more than 9 in a place. For example if you have 16 tens you regrouping 10 tens as one hundred and leave the 6 tens in the tens place.
2. Adding from left to right
This strategy involves adding each place separately then finding the sum of all the places. Many students might not choose this strategy when given an option, but it does tell me about your understanding of the value of the digits in a place. Take a look at the sample below. When we are adding the thousands the answer ends in 000, hundreds 00, tens 0 and ones no zero.
3. Adding by making an easier question
This strategy was the most challenging. Applying this strategy involves understanding the distributive property of addition. Solving a simpler question often help you understand strategies with larger numbers.
+2 -2 +1 -1
7 + 8 = 15 9 + 6 = 16 10 + 5 = 15
In each of these questions I'm just moving over or redistributing the numbers. Think of two piles of candies. One has 7 the other has 8. I can move 5 candies from pile and put it in the other pile. The pile I take the candies from has 5 less candies. If you don't, then the total candies changes and it cannot.
Adding numbers with lots of zeros is easy so that's why we often use this strategy when one addend has a 9 in the ones place.
Subtraction
4. Subtracting using the standard algorithm / regrouping
This strategy only posed a problem when the minuend had zeros. Subtraction across zeros requires an understanding of regrouping 1 of a place as 10 of another.
5. Subtracting by making an easier question
To apply this strategy you need to understand the meaning of the word difference when referring to subtraction. Difference is the amount between two numbers. When we make an easier question we make the subtraction easier keeping the distance the same. You can shift the minuend or subtrahend forward or backwards but you must shift both by the same amount.
Let's say you and your friend are walking to school. If you both walk at exactly the same speed and leave your houses at the same time you will be the same distance apart at any point on the way to school.
6. Finding the difference between two numbers by adding up
Some of you did the number line correctly but you didn't add up all the hops. You didn't find the difference (answer)!
I find it easier to hop to the nearest 10, then nearest 100, then nearest 1000, then to the minuend. You don't have to hop exactly this way as long as you get the correct difference.
7. Estimating
The last part of the test involved estimating. Estimating uses the skill of rounding. We round numbers to the places that have the most value (usually the two greatest - thousands or hundreds). We also used a strategy that involved rounding only one number and leaving the other the same.
The mistakes you make on your test are sometimes a window into the way you are thinking and your level of understanding. You will be given a review sheet on Monday to help with studying.
For the test on Thursday, you must apply all of these strategies to solve and create addition and subtraction problems. Most of you can create an addition problem, but the different subtraction problems pose a challenge. You must think of subtraction as not only taking away or what is left, but the DIFFERENCE between two numbers. Here are a few problems for practice for both grades.
Some are two-step problems. Do not use a calculator.
- Pancake Tuesday.... A pancake or two will be made and served to you first thing in the morning.
- Ash Wednesday Mass @1:30 in the gym
- Addition and subtraction skills test Wednesday
- Addition and subtraction problem solving test Thursday
- Physical Education Tuesday and Thursday (last week for gymnastics)
- Dry erase marker for math class (old sock for erasing)
