This idea comes from Brandy of Some of This and Some of That. She used this bean bag toss game with her school-age daughter, but it could easily be adapted for preschool-age little ones.
In her post, she says, "I am so excited for the Valentine party in my daughters classroom. I am going to have two kids toss a bean bag on two different numbers, and the two of them will have to add the numbers together to get the sum. I just took four big posters and taped them together, cut out a heart and put numbers on the heart.
"I had my daughter test it out just to make sure they would think it was fun (never know!) and she loved it. Her and I played it for a long time and had fun and learned all at the same time."
This would be a great game to introduce numbers to little ones. Simply have them throw the bean bag on the heart (or whatever shape you make!) and then say the number that it lands on. This could be done in a very informal, undemanding way. As your little one becomes more familiar with numbers, you can ask them to identify the number the bean bag lands on. Once they are fairly comfortable with numbers, you could switch the game by having your little one tell YOU a number and you have to land the bean bag on the number.