Decoding decimals

Sinny Mole

Last year I attended an external workshop in Rajkot organized for primary math teachers. After the introductory session, the facilitator asked the participants for a topic they considered a challenge to teach. Most teachers named one topic – ‘decimals’.

The concept of ‘decimals’ is difficult for the children to understand. Children often get confused when asked to compare decimal numbers. When comparing and ordering decimals, children apply the whole number place value concept to the decimal numbers as well. For example, to them 0.32 seems greater than 0.4.

All of us quickly recognize that 0.5 and ½ are simply different representations of the same quantity. Some teachers simply point out that the two representations are “the same thing”. But, it is difficult for primary grade children to visualize the connection between the two different systems – fractional representation and decimal representation. The way we communicate concepts to the children matters a lot. It is very important to explain that both decimal numbers and fractions represent the same concepts. A deep understanding of decimal number scan develops only when children have the opportunities to explore decimal concepts concretely and pictorially and then relate them to fractions. To help in this understanding, teachers should develop classroom activities for modelling base 10 fractions and expanding the base 10 number system. Before teaching place value, children should be given enough practice for conversion from decimal representation to fractions and vice versa. Remember, decimal numbers are simply another way of writing fractions and hence teachers must demonstrate the connection between the two.

Generally, primary grade children prefer active learning experiences that allow them to explore and construct mathematical ideas. The use of concrete materials provides a lot of opportunities for children to see that mathematics is practical. A well-planned and organized classroom session paves the way for an enjoyable learning experience that stimulates curiosity and interest of all children.

Activity – 1

Hunt for decimals
Newspapers are good sources for demonstrations of decimal fractions. Stock exchange rates and city min/max temperatures are also represented as decimal fractions. Children can find and mark them with a colour pen.

The teacher can instruct the children to search and record examples of decimal fractions observed at various places outside the classroom.

Vocabulary of decimals
Decimal Point
Decimal Part
Thousandths
Hundredths
Tenths
Place Value
Whole Number Part
Unlike Decimals
Equivalent Decimals
Like Decimals
Decimals

Activity – 2

Children need a firm understanding of place value representation of whole numbers and a good knowledge of working with fractions. They need time to understand the concept of a decimal point and a decimal notation of a number. To reinforce their understanding the teacher can do the following
activity:
Distribute a square paper or a graph paper to each child. Ask the children to draw a 10×10 cm square and divide it into ten equal rows and columns. It is important for the children to understand that the large square represents one whole, 10 strips make one whole and 100 smaller squares make one whole. 10×10 grids are useful models for working with tenths and hundredths.

Teachers should give sufficient time for children to identify the shapes. Ask them how many make three-tenths of it and so on. Then the teacher can ask the children to colour some portion of the square, say the portion corresponding to twenty-five hundredths of the square. Then ask them how many tenths of the square are there in the shaded portion. Here they identify the shaded portion as 2 tenths and 5 hundredths. By now they understand that we can denote 2 tenths and 5 hundredths as 0.25.

Teachers should keep in mind that when giving children problems that use the strips-and-squares model, the aim should be to develop concepts rather than rules.

Math teaching tools
Nowadays a variety of readymade teaching tools are available in the market that are quite helpful for math teachers. To my knowledge ‘Jodogyan’ is one of the best resources available in our country. Comparison, ordering, addition and subtraction, etc., can be well demonstrated with a ‘Decimal kit’. I do believe, you will love to use such teaching tools in your classroom to make math learning more interesting and effective.

Reference: Jodogyan Resource Centre, www.jodogyan.org

The author has been math teacher and Assistant Coordinator, Primary-2 at Kokilaben Dhirubhai Ambani Vidyamandir, Reliance Greens, Jamnagar. She can be reached at sinnymolepm@yahoo.in.