When learning a new number in class, I do not give them the number by itself, I use that number in a problem. I believe that I do not have to spend 15 minutes on learning about number 5, for example, just because my children do not know number 5.
This is what I did. I used 5 in a problem such as : Kolo has 5 soft toys and Marii has 2 soft toys. How many soft toys altogether that they have?
Children are learning number 5 better when it is used in a context. It was hard at the beginning but I have realised that children enjoyed exploring using familiar contexts; and they learned to know and identify numbers faster in this way rather than learning the number in isolation.