Regardless of their size and shape, most toddlers between 18 to 24 months reach developmental milestones at about the same time. Between 18 and 24 months, your toddler’s brain is developing nerve connections and pathways that are affected by all the things they try and learn, and their experiences of life. They copy you and other people and repeat things they hear.

She will probably start being able to find hidden things, sort shapes and colours, complete familiar rhymes and parts of songs and name items in books. 

Most toddlers are walking and probably running by 18 months and most will have started walking up and down stairs with your help. Although he will probably like to play near other children, they may not always want to play with them. They will become better at kicking or throwing a ball, scribbling with a pencil and creating structures with blocks.

When searching for toys look for 

Toys that get them moving to help them hone their walking and running skills as well as burn some of that toddler energy. Also look for simple toys that can teach lessons like cause and effect, or recognition of letters, numbers, and shapes.