4th Grade - Math

LESSON PROBLEM: Computation: If you had five rice cookies, and you purchased a package of 12 cookies, how many cookies would you have altogether?


STUDY GUIDE

To be able to add mentally is very helpful and fast.  It is quicker than any calculator. If you have not learned it yet, do not worry.  Keep practicing, and you will soon be able to add all of the addition facts up to 20.

You have 5 quarters left from last month's pocket money, and you have 8 more quarters from this month's money.  You want to spend it on rice treats.  How much money do you have for the rice snack?

It does not matter which direction you use in order to add.  In this case we want to add 5 and 8.  We know that if we start counting from 8, we will count only 5 more.  This is quick and easy.  So count 9, 10, 11, 12, 13.  The answer is 13.

If we had started counting from 5, and counted 8 numbers beyond, our answer would still have been the same.  Start counting: 6, 7, 8, 9, 10, 11, 12, 13.  Again the answer is 13.

When you want to add two unequal numbers, take the shorter route and add the smaller number to the larger one. 

Using the table do the examples that follow. Try to learn the table, so that it is easier to remember the sums that add up to 20.

+ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20  
2 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20    
3 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20      
4 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20        
5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20          
6 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20            
7 7 8 9 10 11 12 13 14 15 16 17 18 19 20              
8 8 9 10 11 12 13 14 15 16 17 18 19 20                
9 9 10 11 12 13 14 15 16 17 18 19 20                  
10 10 11 12 13 14 15 16 17 18 19 20                    
11 11 12 13 14 15 16 17 18 19 20                      
12 12 13 14 15 16 17 18 19 20                        
13 13 14 15 16 17 18 19 20                          
14 14 15 16 17 18 19 20                            
15 15 16 17 18 19 20                              
16 16 17 18 19 20                                
17 17 18 19 20                                  
18 18 19 20                                    
19 19 20                                      
20 20                                        

In the table above, find the 5 in the first row, and the 8 in the first column.  If you move to the right of 8 and down from 5, you will come to a square where the two meet.  This square has the number 13, which is the sum of 5 and 8.

Here's another example.  You are inviting 9 cousins and 11 friends to a rice snack party.  You want to find out how many rice snacks you will want to buy so that each one of them gets one piece.  Add 9 and 11.  Using the table, move down from 9, and right from 11. The row and the column meet at 20.  So 20 is the answer.  

Now take 11 in the first row and 9 in the first column.  Move down from 11 and go right from 9.  Again the two  meet at 20.

Do the following exercises using the table.

  1. In a rice cooking competition, there were 12 entries for pilafs, and 7 for risottos.  How many total entries were there?
  2. At a picnic there were 5 servings of rice noodles, and 9 servings of rice pilafs.  How many total servings of rice dishes were there?
  3. At a rice snack fair, Jimmy purchased 9 sweet and 7 salty snacks.  Find the total number of rice snacks that he purchased.
  4. Susan's father, a Missouri rice farmer, planted long grain rice on 14 acres, and short grain rice on 5 acres.  On how many acres did he plant rice?
  5. Janet purchased 9 kilograms of long grain rice from one store and 5 kilograms of basmati rice from another store.  Find the total amount of rice that she purchased.
  6. Peter worked on one Texas rice farm for 9 days and on another for 7 days.  Find the total number of days that he worked on rice farms.

Now practice some addition facts.






ACTIVITIES

Sit with your friend or somebody from your family. Have some rice snacks handy. Now call out a number, and ask your friend to do the same. Now try to find the total of the two.

Let's pretend that you said 7 snacks, and your partner said 9 snacks. Now try to add the two numbers (the numbers 7 and 9). When you get your answer, bring your rice snacks out and put them on the table. Ask your partner to do the same. Count the snacks. The total number of snacks would give you the answer.

Continue with the game and have fun. For more practice, try this worksheet.



EXTENDED LEARNING

If you are told to add two numbers, say 15 and 7, without the help of any objects, how would you go about it?



VOCABULARY
  • add
  • plus
  • altogether
  • total
  • count
  • forward
  • column
  • row
  • calculator
  • parboiled
  • unequal


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