Getting the point - Number link
This is a level 3 number link activity from the Figure It Out series. It is focused on writing fractions as decimals. A PDF of the student activity is included.
About this resource
Figure It Out is a series of 80 books published between 1999 and 2009 to support teaching and learning in New Zealand classrooms.
This resource provides the teachers' notes and answers for one activity from the Figure It Out series. A printable PDF of the student activity can be downloaded from the materials that come with this resource.
Specific learning outcomes:
- Write fractions as decimals.
Getting the point
Achievement objectives
NA3-1: Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages.
Required materials
- Figure It Out, Link, Number, Book Two, "Getting the point", page 20
- a Slavonic abacus or a beads frame (optional)
See Materials that come with this resource to download:
- Getting the point activity (.pdf)
Activity
The important feature of this activity is that the whole (in this case, a beads frame) is separated into two parts in the corners. These parts can therefore be represented as a fraction of 100 if the whole is considered to be 100 out of 100.
Make sure that the students notice that the fractions shown in question 1 are complementary because they always add to 1 or 100/100 . A useful warm-up activity may be to have the students make a chart showing some addition complements to 100, for example:
- 10 + 90 = 100, 20 + 80 = 100, 30 + 70 = 100, …
- 5 + 95 = 100, 15 + 85 = 100, 25 + 75 = 100, …
You could also explore question 2 by using a calculator as well as the abacus mentioned in the question. If the students press 1 ÷ 3 and = on a calculator, the display will show 0.3333333. If they then multiply this by 3, the calculator display will show 0.9999999 rather than 1. This rounding error is caused by the problem that 1 cannot be divided by 3 exactly in a decimal system, and so a recurring decimal is formed.
1.
a. 70/100 or 7/10 = 0.7 30/100 or 3/10 = 0.3
b. 40/100 or 4/10 = 0.4 60/100 or 6/10 = 0.6
c. 25/100 or 1/4 = 0.25 75/100 or 3/4 = 0.75
d. 63/100 = 0.63 37/100 = 0.37
2.
No, because 100 will not divide evenly by 3.
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