Part-whole models are used to help children to see the relationship between a number and its component parts.
For example: 37 can be made up of 30 and 7
It can also be made up in other ways, such as 27 and 10 or 20 and 17.
The key to working successfully with larger numbers is to understand that a digit’s value varies according to its position in that number. Place value grids are great at helping with this, as are part-whole models.
In Year 4 children are expected to work with 4-digit numbers. A good way to help children when looking at a 4-digit number is to not read it as a series of digits (like a telephone number eg three two four eight) but as the number three thousand two hundred and forty eight. The latter reinforces the place value.
We have a great selection of pages on partitioning and place value in Year 4, including our latest set on partitioning numbers using part-whole models.