Simple Logical Problems
Some problems cannot be solved by simply counting. We may need to look at clues, compare information and think carefully before choosing an answer.
This kind of careful thinking is called logical thinking.
Learning Objectives
- Understand how clues can help solve a problem.
- Compare information carefully.
- Use simple reasoning to choose an answer.
- Explain why an answer makes sense.
Using Clues
A clue gives us information that helps us find an answer. We should read or listen to every clue before making a choice.
Riya has a red ball and a blue ball. Her red ball is bigger. Which ball is smaller?
Answer: The blue ball.
Comparing Information
Sometimes we can solve a problem by comparing two or more things. Words such as bigger, smaller, more, fewer, longer and shorter can give us useful clues.
We need to pay attention to the exact words used in the problem.
Thinking Step by Step
A simple logical problem can be easier when we solve it one step at a time.
Aman has 3 red pencils and 2 blue pencils. Which colour has more pencils?
Step 1: Look at the red pencils → 3.
Step 2: Look at the blue pencils → 2.
Step 3: Compare 3 and 2.
Answer: Red pencils.
Checking the Clues
After choosing an answer, check whether it agrees with all the information given in the problem.
If an answer does not fit one of the clues, we should think again and find another answer.
Common Mistakes
- Do not ignore an important clue.
- Read the whole problem before answering.
- Do not choose an answer only because it looks familiar.
- Check your answer against the information given.
Practice
1. Ravi is taller than Mohan. Who is shorter?
2. A box has 5 red balls and 3 blue balls. Which colour has more balls?
3. A pencil is shorter than a ruler. Which is longer?
4. Why should we read all the clues before answering?
Try It Yourself
Choose three objects around you. Give each object one simple clue, such as bigger, smaller, longer or shorter. Ask someone to identify the correct object using your clues.
Quick Revision
- Logical thinking means thinking carefully about information.
- Clues help us solve problems.
- Comparing things can help us find an answer.
- We should check that our answer fits all the clues.
Next Step
You have learned how to use clues and comparisons. In the next lesson, you will see how mathematical thinking is used in everyday situations.