This Autumn ordering size sheet can be printed out, but are used as an example of the sorts of objects that you can talk about and measure. Use language such as 'which is longer, which is shorter, taller, etc.'
Go on a nature walk and try to find some flat leaves. Ask your child to draw numbers 0-10 (or 0-20 if your child is confident) and put them in the correct order. You could mix them up afterwards and see if they can restore them to the correct order. You could use the leaves as a base for lots of maths counting, such as choosing the leaf with '4' on and counting 4 conkers, building a tower with '1' block then '2' blocks then '3' blocks and so on.