Comparing shells


You can help your child to make a physical graph and talk about it using, ‘the same’, ‘more than’, and ‘less (or fewer) than’, ‘difference between’ to compare amounts.

What you need:

A collection of a various shells, leaves or other natural materials.

What to do:

Have your child make a pile of approximately 20 shells in front of them and sort them into different kinds.

Ask your child to arrange them in (parallel) rows of each kind. You may need to demonstrate, and support your child to arrange the shells evenly so comparing the numbers of shells is made easier.

   Like this,

rather than like this
(the row of the six small periwinkle shells
is shorter than the row of 5 mussel shells)

Name the shells together (eg. cockle shell, mussel shell, scallop shell, periwinkle, turret shell, tulip shell) and talk about their features 

Have your child say how many they have of each kind what else they can see. Use prompts like: ‘Tell me what you notice about the number of mussel shells and cockle shells.’

Listen for statements such as:
    “There are two more shells than cockle shells.”
    “There are two less cockle shells than mussel shells.”
    “There’re five mussel shells and that’s two more than the cockles. There’re only three of those.”
    “There’s five mussel shells and three cockle shells so the difference is two.”
    “If there were two more cockle shells they’d be the same.”

Continue with prompts, having your child make a range of comparisons between the different numbers of each kind of shell.

Invite your child to make any other observations about their graph such as:
    “There are six different kinds of shells.”
    “ Altogether there are 19 shells. I know that because…”
    “More than half of the shells are mussels and periwinkles.”

If you have a cell phone or iPad, photograph the display, and then have your child return the shells to the pile. Suggest that they make another selection, graph with these and see if the graph looks like the previous one (photographed).

Encourage further comparison statements.

What to expect your child to do:

  • Correctly count the number of shells in each group.
  • Make statements using the language of same, more than, less than and difference between. 
  • Correctly state how many more shells should be added to, or taken from any row to make it the same in number as another identified row.

He Kupu Māori:

compare whakatairite
how many? e hia?
shell kotakota
category, group ropu

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