In word problems, bar models help children decide which operations to use or visualise problems.
The bar model is central to maths mastery, it can be the pictorial stage in the concrete, pictorial, abstract approach to learning. Bar models will not, however, do the calculations for the pupil; they simply make it easier for pupils to work out which calculation must be done to solve the problem.
The following article from Third Learning Space provides a more detailed explanation:
I like using the equipment, especially Numicon and Deines, it helps me see the maths. (Year 3 pupil)
I like when we write in the (White Rose) books. There are pictures to help you if you need them and sometimes you do hundreds of questions in a lesson! (Year 3 pupil)
Sometimes I do drawings to help me solve a problem. (Year 4 pupil)
Maths is my favourite subject. It really makes you think! (Year 4 pupil)
Our teacher asks us really challenging questions but always gives us time to think. (Year 5 pupil)
I love TTRockstars. My brain used to get muddled with times tables but now I get faster every week! (Year 5 pupil)
My favourite part of the lesson is using the White Rose exercise books. The questions always start off quite easy but then they quickly get really challenging. (Year 6 pupil)