Length

Dear Parents,

It has been a fun beginning to the topic where we got to compare the recumbent length and height of some children in 2 Thinker.

Nonstandard units: The children were given ice-cream sticks, paper clips and base-ten cubes as nonstandard units to measure some objects. They are encouraged to experiment with the appropriate unit that has the same attribute as that to be measured. For example, we would not want to measure the thickness of a page with an eraser or the length of a classroom with a paper clip.

Another important concept is the actual measurement using nonstandard units is always approximate. Look at the picture below, the length of the pen is closer to 4 paper clips than 5 paper clips long. We say that the length of the pen is about 4 paper clips long.

Below are some common mistakes to avoid when placing nonstandard units:

When two children accurately use the same unit to measure a particular object, both should get the same number. However, if they use different units, two different answers can be correct. Let's see...

It is helpful to discuss this idea when using body parts as arbitrary units. An example is the measuring of the width of the classroom in shoe lengths. Once the children understand what unit means, they can appreciate the problems associated with trying to communicate such measures outside their class or school. They will come to see that it is difficult to communicate measurements done with nonstandard units to other people. So, there comes standard units.

We read the book 'How Big is a Foot?' in class.

Your child needs to know:

• metre (m) - unit of measure for length
• estimate and measure 1m
• name objects that are more than 1m long and objects that are less than 1m long
• estimate and measure the lengths of objects in metres

Concepts in green were covered in Primary One.

Comparing two or more objects

Comparison of Height (Measuring from the top to the bottom) 

1. taller than (comparison of two items; with 2 letters 'e r' to remind us about this property)
2. tallest (comparison of three or more items; with 3 letters 'e s t' to remind us about this property)
3. shorter than
4. shortest
5. as short as
6. as tall as

For points 5 and 6, some children are still misled by the word 'short' or 'tall'. Please reinforce that these words wants us to identify the two items that have the same height.


 Comparison of Length (Measuring from the left to the right) 

1. longer than (comparison of two items; with 2 letters 'e r' to remind us about this property)
2. longest (comparison of three or more items; with 3 letters 'e s t' to remind us about this property)
3. shorter than
4. shortest
5. as short as
6. as long as

For terms 5 and 6, some children are still misled by the word 'short' or 'long'. Please reinforce that these terms wants us to identify the two items that have the same length.