I'm not a maths specialist, but yes enormous numbers of children struggle with division-even some year 8s! Modelling is good but it's not the type of skill you can model once & children 'get it'. Lots of modelling, lots of reinforcement /practice & above all time is what I've found. Also personally I think for year 5 who are not natural mathmatecians a division calculation with an answer with an expected decimal answer is far too complicated. Simple ones with whole number answers to practice, then ones with simple remainders, but decimals?! Perhaps a mathsspecialist teacher might advise differently. I find if children don't 'get it' after a week, we leave it & revisit at a later date rather than them become too disheartened.