Chapter 8 Adding and Subtraction Has Just Gotten Bigger!
Chapter 8 Adding and Subtraction Has Just Gotten Bigger!

Chapter 8- Adding and Subtracting Has Just Gotten BIGGER!!             Can you believe that this is the same child that started in the beginning of the year just learning how to make numbers? Well we are kicking things up a HUGE notch to get ready for Second Grade. This chapter introduces finding the sums and differences of TWO- digit numbers without regrouping (or trading in) and two- digit and one-digit numbers with regrouping (trading in). WOW!! Can you believe it? We have been training hard for this and now the day is here to put all that we have learned to the test. Take things slow and easy and we all will emerge victorious!! Use this website to help practice at home.

VOCABULARY

ones - the value of a digit in the ones position on a place value chart

tens - a group of ten ones otherwise known as a bundle ·        Adding groups of 10 is the almost the same as adding numbers less than 10.

·        When adding tens to a two –digit number, only the TENS digit changes. An example of this is 3 7 +10 = 4 7. When we were doing this with money we would say that “A dime is 10 so change the tens”. The same idea applies here. We should be able to get through these no sweat!

·        When adding two digit numbers ALWAYS, ALWAYS, ALWAYS count the ones side first and only add the ones to the ones and the tens to the tens. Here is an example:

21

+18

9 ( 1 + 8 = 9)

30 ( 20 + 10 = 30)

39

This is the process that actually is going on in the child’s head. We do not teach this way because then we would lose our minds. Instead we use tens and ones sticks first while I am writing on the board the traditional way like written above. Doing this together lets the children see the concrete version that they need with the written way that will be the way that they will be dong this in the future. It also allows every learner to use what they need to figure out the equation. We make a BIG deal about counting the ones first because there will be a time when we will have to trade in for a ten… but not yet. When there is 9 or less in the ones we say that we are “Safe” and then move on to adding the rest. When I am writing it on the board I actually draw a line down the middle of the equation so that the children can see each side as different.

45

+12

-------

Anyway that works for your child is fine by me!!

·        Now we are there for “trading in”. When there are 10 or more in the ones we sound the alarm, “ WOO, WOO, WOO” and trade in the ten ones for a tens stick. We actually pick up the ten ones first then put them back and at the same time pick up a tens stick. It is not allowed to have a ten or more ones in the ones side. L

2.    Subtraction

The same rules apply to subtraction, yet this always seems to be an area where children can get pretty tricked up. The key here is to take your time and go slow so that the concepts get in those brains.

.

·        Subtracting groups of 10 is the almost the same as adding numbers less than 10.

·        When subtracting tens to a two –digit number, only the TENS digit changes. An example of this is 3 7 - 10 = 2 7. We should be able to get through these no sweat after working with all of those adding ones that are the same idea!

·        When subtracting two digit numbers ALWAYS, ALWAYS, ALWAYS count the ones side first and only subtract the ones from the ones and the tens from the tens. Does this sound familiar?

Again, we use tens and ones sticks first while I am writing on the board the traditional way like written above. Doing this together lets the children see the concrete version that they need with the written way that will be the way that they will be dong this in the future. It also allows every learner to use what they need to figure out the equation. We make a BIG deal about counting the ones first because there will be a time when we will have to trade in for a ten… but not yet. When there is 9 or less in the ones we say that we are “Safe” and then move on to adding the rest. When I am writing it on the board I actually draw a line down the middle of the equation so that the children can see each side as different.

45

-12

-------

Anyway that works for your child is fine by me!!

·        Here comes the tricky part. When count the ones first there are times when we do not have enough ones to finish out the equation, Again, we sound the alarm and pick up the 10 stick and trade it in for 10 ones and out them on the tens side. I know that it seems like we are going against the rules here, but it is only for a short time so we can get away with it. This is the area where there are a lot of mistakes, so if you can practice at home with the tens and ones or dimes and pennies instead of crossing off as we all learned to do that would be extremely helpful.

Activities for Chapter 12

1. Different Ways to Add and Subtract

Materials: connecting cubes or tens and ones materials or dimes and pennies.

Procedure:

1.    Write 20 + 15 on a piece of paper and tell a simple adding story problem such as : “ I started the game with 20 marbles. Then I won 15 more marbles. How many marbles do I have altogether?”

2.    Ask the child how you can use the cubes or tens and ones or dimes and pennies to solve the problem.

3.    Have the child explain how he used the cubes and then write with the child how it would look with the numbers.

4.    Repeat with a simple subtraction story such as: “There were 36 horses in the barn. 15 horses ran into the field. How many horses are left in the barn?

5.    It is also helpful to discuss what key words are letting the child know if he should add or subtract.

Materials: connecting cubes or tens and ones or dimes and pennies

Procedure:

1.    Write 14 + 11 and 25 +17 on a piece of paper.

2.    Have the child use the items to demonstrate each problem.

3.    The child then solves each problem and explains how he solved using pictures, numbers and words.

4.    Make sure that the child is counting the ONES first each time and sounds the alarm if he has to trade in for a ten.