ordering decimals lesson

28 Dec 2013


The aim of this lesson is to develop students’ understanding of ordering decimals. This is achieved by considering the following set of words.

The idea is that students discuss methods for sorting words and then apply these same methods to ordering decimals. The lesson has a large amount of literacy throughout and has strong cross-curricular links. I have recently taught this lesson with sets 2 and 5 (of 6) in year 7 and the rest of this post gives some details of these lessons.

starter - “what do you think this lesson is about?”

There were a vast range of suggestions, with students predominantly trying to find a connection between the words themselves.


one - “sort the words”

With no other instructions, students set about ordering the words in a variety of different ways. These included

… yet not a single student suggested sorting alphabetically.

two - “sort the words so that everyone has the same list”

At this point I asked students to write a set of clear and detailed instructions for their method of sorting. Students then swapped books and followed their partner’s instructions to the letter and compared lists.

This was the starting point for a discussion about the best way of ordering the words, I picked some students’ instructions and the class followed them and compared their lists. The aim was for all students to generate the same list as each other. Eventually we considered a commonly used method; sorting alphabetically.

three - “describe how to sort the list alphabetically”

All students were confident with how to order words alphabetically, but there were a surprising number of students who thought that a dictionary was ordererd by word length. This encouraged a discussion about how a dictionary is ordered and how it differs from a Scrabble dictionary. This part of the lesson was concluded by considering the pros and cons of each type of dictionary.

four - apply the same skills to numbers

Finally, we talked about how to order

and the idea that the length of the decimals doesn’t necessarily contribute to their size. The set 5 class found it useful to include additional zeroes as placeholders to make all of the decimals the same length. The lesson then continued with practising ordering decimals.

on reflection