For a baby a simple games work best. It depends on the age.
Newborns love looking at faced. Sometimes when you stick out your toung they will too.Reading so that they can hear your voice change poetry type books are great like brown bear
about 3-6 months they like games like peekaboo. They will be a bit more active so toys that are simple to work are great. I found that at this age babies liked looking at bright books that are very simple(like a picture of an apple)
from 6-12 months they are on the go.
safe kitchen items like pots spoons containers. I filled pop bottles with water added food color and sparkles and small toys if I had them.
blocks,stacking rings nesting cups are the best toys.
from 12-2
by this age most kids are learning to scribble so fat washable crayons are great. Dolls and trucks work for both boys and girls. If you can find one a baby bath tub with water for the doll. A baby bath tub can be filled with oats,paste,rice to make a sensory table.
3 three year olda are more independent so things like dress up, fake adult like items, easy games like candy land and memory. They like to watch tv so it's easy to protend that they are a "person" off of a show. Cut and paste are great for getting ready or school. Give them just scrapes and let them go at it. Play dough is great too at this age because most likly they won't eat it!
So much to do with them so little time
