Dominoes are a great resource for children and here is just one set of ideas as to how they can be used. Take a pile of dominoes (it does not have to be the whole set) and sort them into two groups: those with a one spot and those that do not have a one spot. A grid can be printed to help with the sorting. Then, other ways of sorting can be suggested, eg sorting into even number of spots and odd number of spots, or a total less than 7, equal to 7 and a total more than 7.
Ask your child to think of other ways that the dominoes can be sorted and try to predict how many will be in each set.