When is a child is between 6-8 months old they beging to develop a pincer grasp. Which is the pointer finger and thumb working together to pick up small objects. This is the age parents are usually encouraged to introduce easy finger foods such as cheerios, or puffs. The main reason these are recommended is because it's great practice, and they dissolve easily in the mouth.
As the child gets a bit older this skill can be advanced some by also including some problem solving skills, and hand eye coordination. We have an awesome "Cheerios" book that I adore. It's a way to make snack time last a bit longer so I can get some stuff done, he has fun, and is practicing important skills!
The book has different pictures made from cheerios. There are empty holes in the pictures where children are suppose discriminate which need cheerios, then put them in the holes. Here is a link to one:
However, you don't need to the book to make this a fun activity. You can easily draw dots on a paper, and have children cover the dots with cheerios. For children a bit older, you can give them a string to put cheerios on. You could even write their name on paper and have them put cheerios on the line!! Lots of great learning activities, and much more fun then doing a worksheet!