I would suggest the Early Years Numeracy Assessment on the Insight portal as it is delivered on a one to one basis and the teacher asks the questions. It gives you good information on what the child understands and what they need to learn next. Also the Assessment for Common Misunderstandings which is also a hands on one on one assessment is good. This resource provides information on what the student knows and what to do to help them achieve the next level. All of the resources etc. are available on the DET website.
Hope this helps