Addition and Subtraction Unit: Update 2

1. Estimating Differences: We use the following three strategies to help us build mental math skills.

A. Front-end estimation: Subtract only the digits in the tens place.

59 – 23
50 – 20 = 30
So, 59 – 23 is estimated to be 30.

B. Round both numbers to the nearest 10.

59 – 23
60 – 20 = 40
So, 59 – 23 is estimated to be 40.

C. Round the last number to the nearest 10.

59 – 23
59 – 20 = 39
So, 59 – 20 is estimated to be 39.

We focus on learning the strategies and practice deciding which strategies gives the best estimate based on the numbers presented in the problem.

2. 3-Digit Subtraction: 

Strategy 1:

402-128=
402-100= 302 (subtract the hundreds)
302-20= 282    (subtract the tens)
282-8= 274       (subtract the ones)

So, 402-128=274

Regrouping or Borrowing Strategy:

402
-128

 3  9  12
402
-128
274

Counting Up:

402-128

 

 

Counting Back:

402-128

Olympic Winter Carnival

Thank you to the nursing students and students from Warman high school for leading us through fun activities this afternoon. Although it was too cold to go outside, they adapted many of their activities for inside. After a long week of many indoor recesses, we are very grateful for their hard work.

Pink Shirt Day and Pink Bracelets

Bullying is a major problem in our schools, workplaces, homes, and online. Over the month of February, and throughout the year, Pink Shirt Day aims to raise awareness of these issues, as well as raise funds to support programs that foster children’s healthy self-esteem. Warman Elementary will be selling Pink Shirt Day bracelets at the school office for $2.00 each. On February 28, 2018, we encourage everyone to practice kindness and wear pink to symbolize that you do not tolerate bullying.

Valentine’s Day

We will celebrate Valentine’s Day by giving everyone in the class a card.  We will be making a mailbag or box of some kind at school and the students will deliver their Valentine’s Day cards on Wednesday, February 14th. If students would prefer to make cards rather than buy them, I have some templates they can use. I will have the students make a class list so no one is missed. You can also use the class composite photo as a class list too.

Addition and Subtraction Unit: Update

Here is a quick overview of what we have been practicing so far in our Addition and Subtraction unit.  The best way for you to see how your child is doing with these concepts is to have a conversation about them and do a few practice examples together

1. Doubles and Near-Doubles Addition Facts:   We spent quite a bit of time practicing our doubles facts as a class and individually.  We focus on doubles because they are often easy to learn and can be a helpful mental math strategy for solving other addition facts that are close to the double. Students practiced solving “near doubles” equations and explaining the strategy as clearly as they can.

Example: (students are asked to show that they can use both of the possible doubles to solve each problem)
6+8=?
I know 6+6=12
6+8 is 2 more.
So, 6+8=14

or

I know 8+8=16
6+8 is 2 less.
So, 6+8=14

2. Making 10:
Example: To solve 6+8  we may think: Take 2 from the 6, leaving 4.  Add 2 to the 8 to make 10, then add the 4 to get 14.

Or, use an adding a 10 fact like the example below.

We know 10+6=16.
8+6 is 2 less.
So, 8+6=14.

We have also been practicing our addition facts that make 10.

3. Related Addition and Subtraction Facts (Fact Families):
Example: If we know 7+6=13 we also know 6+7=13, 13-6=7, 13-7=6.  Using “fact family” knowledge is often most useful for students to solve subtraction equations by thinking of the related addition fact.

4. Estimating Sums: We use the following three strategies to help us build mental math skills.

1. Add only the digits in the tens place.

59+23
50+20=70
So, 59+23 is estimated to be 70.

2. Take one number to the closest 10.

59+23
60+23=73
So, 59+23 is estimated to be 73.

3. Take both numbers to the closest 10.

59+23
60+20=80
So, 59+23 is estimated to be 80.

We focus on learning the strategies and practice deciding which strategies gives the best estimate based on the numbers presented in the problem.

5. Three Digit Addition:

We continue to work hard at maximizing our learning about numeracy while exploring addition and subtraction of three digit numbers. The students have many strategies for working with three digit number equations.  The samples below are examples of some of the strategies we have been working with. Please keep in mind that these are just basic examples and individual students will often take apart and re-construct the numerals in unique ways that match their understanding of numbers. When this happens it is often a very good sign that they are good mathematical thinkers. There is a big difference between blindly following steps to get the correct sum and being able to make efficient adjustments to strategies based on the problem that is presented.  

Addition: 

368+257=
300 + 200 = 500 (add the hundreds)
60 + 50 = 110       (add the tens)
8+7 = 15                (add the ones)
500 + 110 = 610  (add your answers from the 100s, and 10s)
610 + 15 = 625 (add answer from the 1s the sum of the 100s and 10s)

Another Variation

   368
+ 257
500  (add the hundreds)
110   (add the tens)
_15     (add the ones)
625

For both addition and subtraction some students need to build/draw base 10 materials to help them visualize what is happening to solve three digit problems.

Skating Fun

We had a great time skating on Wednesday. Thank you to those that were able to volunteer their time. Thankfully Mrs. Neufeld took a couple pictures while the students were skating. I will try to do a better job taking some pictures when we go again on March 2.

Grade 3 Skating

A newsletter about skating will be sent home today.  Our class goes skating on January 24,  and March 2, in the afternoon.  If you are interested in volunteering to help tie skates or skate with the students, please let me know. Click the link below if you need a copy of the letter.

Grade 3 Skating Letter

Some Upcoming Dates

January 11 – Book orders due

January 24 – Afternoon skating at Legends Centre
(The original date sent home in the planners was wrong. Planners have been updated)

January 31 – No classes for students

February 19 – Family Day (no school)

February 20 t0 23 – No classes for students

March 2 – Afternoon skating at Legends Centre