Skip to main content

Using Legos To Provide A 3D Visual On Using Block Diagrams To Solve Primary 3 Arithmetic Problem Sum

Boys usually learn faster if they are hands on and can visualise the problems. As such, I usually use Legos to explain maths concept to my son so he can visualise the working and the solution.

Last night, we were going through the maths homework and there was this arithmetic problem sum that required the understand of the concept of units. It only dawned upon me in the morning after how I could have used Legos to explain the concept to him, which I will be showing him later today.

The Problem Sum

There are three fishes. Fish A cost three times as much as Fish B. Fish C cost $4 less than Fish B. The total cost of the three fishes is $46. Find the cost of Fish A. 

Step 1: Compare cost of Fish B and Fish A.

Let's take the 1-whole Lego block to represent the cost of Fish B.



Since Fish A cost three times as much as Fish B, the cost of Fish A cost 3 x 1-whole Lego Block.


Step 2: Compare cost of Fish B and Fish C

 As Fish C cost $4 less, let's the 3/4 Lego block to represent the cost of Fish C.


The $4 difference can be presented by the 1/4 Lego Block.

Step 3: Cost of 1-whole Lego Block

To find the cost of a 1-whole Lego Block, I will need to the cost of Fish B to be represented by a 1-whole Lego Block. This will then allow me to take the Total Cost of the Fishes to be presented by 5 x 1-whole Lego Blocks and I can divide this Total Cost by 5 to find out the cost represented by 1-whole Lego Block.

However, the cost of Fish C is short of a 1/4 Lego Block (=$4). As such, I have to add the 1/4 Lego Block to Fish C to make it a full 1-whole Lego Block.

If I add 1/4 Logo Block to Fish C, I would also need to add 1/4 Logo Block to the total cost.

Since the 1/4 Logo Block = $4, I add $4 to the total cost of the Fishes which is now $50.


Step 4: Determine the value of 1-whole Lego Block

The value of 1-whole Lego Block can be determined now by $50/5 = $10.

Since cost of Fish B is represented by 1-whole Lego Block, Fish B cost $10.

Step 5: Calculate the cost of Fish A

As the value of Fish A is represented by 3 x 1-whole Lego Blocks, cost of Fish A is $10 x 3 = $30.

The question could also ask to find of cost of Fish C. To do this, simply take $10 - $4 = $6 as from the block diagrams.
Labels:

Comments

Post a Comment

Popular posts from this blog

Primary 3 Level 2 Maths Money Problem Sum

Below is a money problem sum for Primary 3. It isn't that difficult to solve when you under the basic approach. Mr Lim went to watch "Disney on Ice" with his two sons. He paid $147.50 for all the tickets. A child ticket cost $30.50 less than an adult ticket. How much does a child ticket cost? Child tickets are of equal parts and the adult ticket is $30.50 more than 1 child ticket. So to make the Adult ticket to be of equal parts with the Child ticket, you have to take away $30.50 from the Adult ticket. If you do this, you also have take away $30.50 from $147.50. $147.50 - $30.50 = $117 All of the 3 parts are now equal and the sum of the 3 parts is $117. So you just take $117 divide by 3. $117 ÷ 3 = $39 As such, each child ticket is worth $39. There could be some variations where question ask for the total of two child ticket which you take $39 x 2 = $78 or your child will be asked the price of the adult ticket which is $39 + $30.50 = $69.50.
Post a Comment
Read more

Chicken And Rabbit Maths Question

They call it the Chicken and Rabbit maths question. The question will start with the total number of chicken and rabbit, and the total number of legs. With this, you be asked how many chicken there are in the farm. The chicken and rabbit can be replace with any two and four legged animal respectively. Example of question - Hussain saw a total of 23 sheep and ducks in a farm. If there are total of 82 legs, how many ducks did he see? Many parents will look to algebra to get the answer. Eg x=sheep, y=ducks, so x+y=23 and 4x+2y=82. As this is P3 maths, you are technically not allowed to use algebra as it is not taught yet and algrebra is Mathematics and not Arithmetic. The other method is to do ratios but it can be a challenge if the numbers get too big.  I found a Youtube Video which explains how to this sum but I am blogging this to keep a record on how to this for posterity. The Explanation and The Working  There are a total of 23 animals in the farm and ...
Post a Comment
Read more

An Age Old Problem

Question Mrs Ismail was 4 times as old as her daughter 5 years ago . How old is Mrs Ismail now if the sum of their present ages is 55 years ? I was initially stumped by the question. I drew the necessary block diagram but "the 5 years ago" and the "present age is 55 years". I gave up on the question and decided to leave it aside for a day. The next day, I had a light bulb moment when it daunt upon me to just add the 5 years to each block to make it a total of 55 years old. If you have drawn the blocks without the +5, I feel you. That was where I got stuck too till that light bulb moment. Once you see this diagram, you should immediately know how to solve this question. Step 1: 55 - (5+5)= 45 The total value of the five boxes is 45. Step 2: 45 / 5 = 9 The value of each box is 9. Step 3: 9 x 4 = 36 Mrs Ismail was 36 years old 5 years ago. Step 4: 36+5 = 41 Mrs Ismail is 41 years old now.
Post a Comment
Read more