Let’s start with a question first:
0.45 _____ 0.8
- Greater than
- Lesser than
- Equal to
If you have chosen option B, then you are bang on! But most students do not think the same way. We asked a similar question to almost 39,000 students of class 7 in various government schools and the results are surprising!
As the table indicates, 60% students opted for option A and only 24% students’ chose option B.
The question checks students’ understanding of decimal numbers, meaning of decimal point and place value of digits of a decimal number. Here most students seem to be confused with 19 and 19th part of 100.
The reason behind this misconception is Whole number thinking. It leads some students to believe, in the context of comparing decimals, that “longer is larger”-for example, 0.37 is larger than 0.7 because 0.37 has more digits. Or some students just ignore the decimal point and compare 219 with 23 in this example.
Use of different representation for decimal numbers and consciously catering whole number thinking can help students learn with understanding. If you wish to explore this further, there is an interesting paper on this topic titled ‘Longer is larger – Or is it ?’ by Anne Roche.
By Janvi Soni – Educational Specialist