3.2 Decimal fractions in the context of measurement

Mathematics

Grade 4

Measurement, space and shape

Module 12

Decimal fractions in the context of measurement

Activity 1:

• To recognise and use decimal fractions in the context of measurement [LO 1.5]
• To estimate, measure, record, compare and order two-dimensional shapes and three-dimensional objects using S.I. units [LO 4.5]
• To estimate, measure, record, compare and order two-dimensional shapes and three-dimensional objects using S.I. units [LO 4.7]

1. Measuring Mass: grams and kilograms: 1 000 g = 1 kg

Hands on: practical work

You may work in pairs or groups for this work. You will need to look at a new box of 100 tea bags and you will need a kitchen scale, one tea bag to work with, a box of cornflakes, a packet of margarine and a brick. You will also need a bathroom scale and a weight-watcher’s scale if possible (so work in a group and each one can bring two items of the above).

1.1 Estimate the mass of the box of tea bags. Pass it around the group. Did some clever person look at the outside of the box? Yes, they have to write the MASS on the outside.

1.2 Now pass the box of cornflakes around.

1. What is its mass? .
2. Which is larger : a box of tea bags or a box of cornflakes? .
3. Which is heavier: a box of tea bags or a box of cornflakes? .
4. Yes, it depends on the size of the box of cornflakes. One can get a box of cornflakes that has the same mass as 100 tea bags.

What would that mass be? .

1.3 Carefully take out one tea bag. Handle it carefully, as it can break easily. Pass it around the group.

a) Estimate the mass of one tea bag. What do you think is its mass, when you

hold it in your hand? .

b) Now discuss in your group: How can you calculate the mass of one tea bag, using the information that you have at present? An adult is not to tell you, please!

Hint: Look at the writing on the box. There’s something there that can help you.

c) Now use the weight watcher’s scale to measure the mass of one tea bag. What is it? (It’s a small mass, and not so easy to read. Maybe your educator

can help you to read it.)

d) Use the kitchen scale to measure the mass of the box of tea bags and the box of cornflakes. Is the writing on the outside of the boxes accurate?

1.4 Now, carefully, pass the brick around. Estimate the mass of the brick. Complete the table, USING “GRAMS” OR “KILOGRAMS” as necessary. Write in “g” or “kg”:

2. Measuring Length and Distance.

Hands on: practical work

You will need a tape measure, a ruler and any other measuring instruments that you can bring (e.g. tape for measuring “Long Jump”. You may work in groups. In each of the following tasks, ESTIMATE the length and write down your estimation BEFORE you actually measure. You may ask a friend to help with the accurate measurement. Write your findings in the table on the next page.

R ecordings: