Step 10 Lesson 5

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Weight Conversion

Objectives

To estimate weights of items.

To learn that there are 1000 g to 1 kg and to understand the relationship between grams and kilograms.

To apply decimals to weight measures.

Resources

Abacus 4 Textbook 1 | Squared paper

Today's Lesson

Main Activity

Think up a few fractions which can be reduced to equivalents with a numerator of more than one and ask your student to find them. For example:

6/8, 4/10, 8/12

Turn to page 65 in Abacus 4 Textbook 1.

Watch the video 'Length, mass and capacity' to understand the different units of measure.

Look at the various creatures in Q1 – 6  and ask your student to estimate and circle the most likely weight. Your student may need to do some practical activity before completing this exercise if they do not have practical experience of weighing, e.g. through cooking or weighing objects. 

Watch the ‘Weight conversion’ video to understand conversions between kg and g using a number line.

Remind your student that there are 1000 g in 1 kg. That means when converting from g to kg, we divide by 1000. Similarly, when converting from kg to g, we multiply by 1000.

As an alternative to the number line, remind your student of how we used our place value columns when we multiplied and divided numbers by 10. (It is important that your child is familiar with this concept). Here, we are going to need to multiply and divide by 1000. They could use the columns as a visual aid if they find this concept difficult. When we multiply or divide by 1000, we move the digit 3 places to the left or to the right (there are three zeros in ‘1000’).

For example:

1500g expressed as kg: we would need to divide the number by 1000, or move it 3 places to the right:

Remind your student that zeros at the end of a number, after the decimal point, are not necessary, unless we are dealing with money. So we can see that 1500 g = 1.5 kg which we can also write as 1kg 500g.

The 0.01s column represents ‘hundredths’ or 1/100.

The 0.001s column represents ‘thousandths’ or 1/1000.

Tell your student that they will give two answers to each conversion. Beside each item weighed, they should answer like this: 

1 kg 250 g = 1.25 kg  

For the items that are less than 1 kg, ask your student to write, for example: 

0 kg 500 g = 0.5 kg  

Ask your student to complete the page.