The numbers 0, 1, 2 are just merely symbols. Children need to understand that these number actually represents quantity of objects and can be counted. Once they understand the concept, then it will be easier for them to learn advance math concepts such as numbers operation, sizes and measurement (https://raisingchildren.net.au/babies/play-learning/learning-ideas/early-numeracy)
You can help them understand numbers concept using this kind of worksheet (referring to the picture above).
Let the children do the activity by providing some pompom, asking them to count the pompom and place it on the black dots accordingly. Laminating the paper will allow the children to practice writing on it by using a white board marker.
(Photo from Alimkids Putra Heights. Contact us here for more info about our Alimkids centres)