4th Grade - Math

LESSON PROBLEM: Computation: If I have fourteen grains of rice and add twelve more grains, how many grains of rice do I have? If my family has five bags of rice and we eat two bags, how many bags do we have left?


STUDY GUIDE

Just about everyone eats rice. I'm sure you have rice in you house. You will need about a half a cup of uncooked rice to work with. Count out twenty grains of rice.

Take one rice grain away from your pile. You do not need to count those grains again to know that you have 19. All you have to do is subtract 1 from 20.
20
- 1
19

Put that grain back so that you have 20 again. Now add a grain from the cup. Don't count all of the grains again. How many do you have?
20
+ 1
21

ADDITION (+)

To add more things to a group, start with the original number and keep counting for as many new things as you have. Let's start with our 20 grains and add seven. Count out the seven grains as you take them out of the cup. How many grains do you have now? 27, right!
20 + 7 = 27
You already knew that you had twenty grains, all you had to do was count seven more after that.

SUBTRACTION (-)

When we subtract, we take things away. Subtraction is the opposite of addition. To subtract start with your original number, and count backwards for the things that were taken away. Let's use our original 20 grains of rice again. We'll take eight out. How many are left? Remember that we started with 20.
Let's count backwards, eight from 20: 19, 18, 17, 16, 15, 14, 13, 12.
20 - 8 = 12

Now try the math problems in the Activity section, and use your rice grains only if you need to.




ACTIVITIES

SUBTRACTION

22 - 6 =
39 - 12 =
14 - 5 =
8 - 2 =
19 - 4 =

ADDITION

20 + 10 =
13 + 8 =
9 + 11 =
25 + 11 =
32 + 9 =
17 + 23 =




EXTENDED LEARNING

Help a friend learn subtraction by explaining how borrowing works to them.




VOCABULARY
  • total
  • addition
  • subtraction
  • grain


Click here to play Rice Rampage!
Rice Farm Animals:
Rice farms have lots of animals. Click here to learn more about rice farms and the animals that live there.
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