4th Grade - Math

LESSON PROBLEM: Computation: You save your things so that you can use them at another time. You keep on putting more and more things in your box or container.

For example, you have 5 rice cookies. You get 2 more and put them in a jar. The next day, you look in the jar and think that there are not as many as there were the previous day. How would you find out whether you have the same number of rice cookies?


STUDY GUIDE

Imagine that you have four rice cookies, and you buy two more.  You keep them in a jar thinking that you will enjoy them some other day with your friends. 

The next day, when you open the jar, you find that there are not as many as you had left from the day before.  You can see there are fewer rice cookies.  Now you need to know what has happened to your cookies.  If there are fewer, then how many are missing? 

How would you find out, if you did not know how to add or subtract?  When you combine things, or put things together, you are increasing their number.  We add the numbers to find out how many there are when the two groups have been put together. For example, you have 2 marshmallow rice treats.  Your sister gives you 1 more.  Now you have 3.

How did you get the answer?   You have 2 marshmallow rice treats.  You get one more.  You count one more beyond 2.  In our counting order, we count 1, 2, 3, 4, 5, 6, and so on.  When you have 2 marshmallow rice treats you are already at number 2.  When you get 1 more, you count one number after 2.  This gives us 3.  To add, we count forward.  To add 1, we count forward 1; to add 2, we count forward 2; to add 3, we count forward 3; and so on.

To add 2 and 2, you count forward two from 2, and reach the number 4.  This means that when you add 2 and 2, you get 4.  In math, we use a symbol that means to add.  This symbol is +. We call this symbol the plus sign.  Whenever you see this sign between two numbers, you add them by counting forward from one of the numbers. Count as many steps forward as the other number.  Look at the following example.

2 + 3 means, you have to count 3 steps further or forward from 2. 

You are already at 2, and you count 3 more.  When starting to count, we say 3, 4, 5.

So when you count three numbers further from 2, you reach the number 5. 

Now you try counting 2 numbers further from 3.  What do you get?

It does not matter which way you add the numbers.  If you add 2 to 3 or 3 to 2, your answer will be the same.  Your Mom gives you 2 marshmallow rice treats and your Dad gives you 3, the total will be 5.  Would it make any difference if your Mom gave you 3 and your Dad gave you 2 marshmallow rice treats?

Try the following problems:

  • 2 + 1 =

  • 1 + 2 =

  • 1 + 3 =

  • 3 + 1 =

  • 2 + 4 =

  • 4 + 2 =

  • 4 + 3 =

  • 3 + 4 =

  • 4 + 5 =

  • 5 + 4 =

Try to learn addition facts with the help of the following table.



+ 0 1 2 3 4 5 6 7 8 9 10
0 0 1 2 3 4 5 6 7 8 9 10
1 1 2 3 4 5 6 7 8 9 10
2 2 3 4 5 6 7 8 9 10
3 3 4 5 6 7 8 9 10
4 4 5 6 7 8 9 10
5 5 6 7 8 9 10
6 6 7 8 9 10
7 7 8 9 10
8 8 9 10
9 9 10
10 10


With the help of this table, you can learn to add one number to another number and find the total.  The numbers in this table do not go beyond 10.

To practice addition facts with the help of this table, choose any number in the first row, and then choose any number in the first column.  To find the answer you move along the squares until you reach the square where the row and the column join each other. 

Look at the numbers in red.  In the first row, 5 is red.  In the first column, 4 is red.  You find the total of the two numbers, move right of 4, and down from 5.  These two meet in the square where you find 9.  This is the answer.

Use the table to find the answers to the following:

  • 3 + 3 =

  • 2 + 4 =

  • 4 + 1 =  

  • 7 + 2 =

  • 5 + 3 =

Did you notice that there is no 0.  Zero means nothing.  When you add nothing to a number what happens?  You have 2 rice cookies, and you do not get any more.  The number of cookies that you have does not change.  You still have only 2 cookies.  2 + 0 = 2

Now practice the following:

  • 1 + 0 =

  • 2 + 0 =

  • 3 + 0 =

  • 4 + 0 =

  • 5 + 0 =







ACTIVITIES

Practice adding different numbers using objects. Then add the same numbers without using objects. Then make your own addition worksheet.






EXTENDED LEARNING

Try to add numbers without using objects, or by counting. Practice learning addition facts, so that you can add any two numbers that total up to 10 without counting or using objects. Play this fun addition game.



VOCABULARY
  • forward
  • count
  • add
  • plus
  • sign
  • math
  • further
  • fewer
  • beyond


Click here to play Rice Rampage!
Anatomy of Rice:
Rice is a seed of cereal (grass) plant used for food. Click here to learn more about the Anatomy of Rice.
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