Solving Problems that Involve Subtraction

Hi, kids. This e-tivity is about understanding what mathematical operation is needed to get the answer of a word problem. It's the second from a series of e-tivities about problem solving. By the end

• you will be able to identify what words indicate subtraction,
• you will learn how to subtract fractions.

Average online time: 25 min

Average offline time time: 10 min

1) What words do you think indicate subtraction in a word problem?
Share with your classmates your ideas, write down your message and the click the shout button

2) Consolidating our thinking

Let's watch the following video, please turn on your speakers



Create your own video slideshow at animoto.com.


3) Solving a word problem

Remember that there are at least three questions you need to ask yourself in order to solve a word problem:

1) What numbers are needed to answer the question?

2) What mathematical operation(s) is/are needed?

3) Does my answer make sense?

María is placing some wood fence along a path that is  10   1/3 feet long.  After finishing her daily work, she has already completed  5   2/3  feet. How many feet are there left for completing the fence?

a) What numbers do I need to answer the question? 10  1/3 and 5  2/3

b) What mathematical operation is needed? subtraction because of the words how many....are left

c) Subtracting 10  1/3  &  5  2/3

d) Answering the question.  There are left 4  2/3 feet.

5) Your Task

You need to invent a word problem that requires subtraction to be solved (hint: use one of the key words here explained). Once you have invented your problem, you need to solve it by following these four steps:

a) Understanding: What numbers do I need to answer the question?

b) Planning: What mathematical operation is needed?

c) Solving the problem

d) Answering the question

Do not forget to post your comment including your word problem and the steps a), b), c), and d) you used to solve it.

See you around!

Solving Problems that Involve Addition

Hi, kids. This e-tivity is about understanding what mathematical operation is needed to get the answer of a word problem. It's the first from a series of e-tivities about problem solving. By the end

• you will be able to identify what words indicate addition,
• you will learn how to add fractions and mixed numbers.

Average online time: 25 min

Average offline time time: 10 min

1) How do you solve a word problem?

Share with your classmates the strategies you use to solve a word problem, write down your message and the click the shout button

2) How do "experts" solve a word problem?
Let's watch the following video, please turn on your speakers

There are at least three questions you need to ask yourself in order to solve a word problem:
1) What numbers are needed to answer the question?
2) What mathematical operation(s) is/are needed?
3) Does my answer make sense?

3) Choosing the mathematical operation to be done
In other words, we need to decide if we have to add, subtract, multiply or divide.
Let's play the following fun game to find our what words indicate addition. Once you are sure about the word, click the check  button to continue with the next word


As you see the following words indicate that addition is required: sum, plus, in all, altogether, additional, extra, increase, combined, add.


4) Solving a word problem
Carlos and María will prepare a delicious milkshake. Carlos has 4  3/5  cups of vanilla ice-cream and María has 8  4/5 cups of chocolate ice-cream. Altogether, how many cups of ice-cream do they have?


a) What numbers do I need to answer the question? 4  3/5 and 8  4/5


b) What mathematical operation is needed? addition because of the word altogether


c) Adding 4  3/5  &  8  4/5




d) Answering the question. Altogether Carlos & María have 13  2/5 cups of ice-cream


5) Your Task
You need to invent a word problem that requires addition to be solved (hint: use one of the key words here explained). Once you have invented your problem, you need to solve it by following these four steps:


a) Understanding: What numbers do I need to answer the question?
b) Planning: What mathematical operation is needed?
c) Solving the problem
d) Answering the question


Do not forget to post your comment.


See you around!