Teaching "in and out" is an important skill that many new skills will be built upon. A child must be able to place something "in and out before they can attempt matching and sorting.
I believe that it is easier to to teach "in" before "out". When I taught Adeline how to put "in" I used the two cookie jars that are shown above. The Oreo jar is no longer sold but it can be found on e-bay. Adeline really enjoyed the Oreos the most because of the sound and texture.
When we first started with teaching "in" we would move Adeline's arm at the elbow and hand over hand have her drop "in". We would then quickly put the lid on the cookie and say "yeah". She would look at us so surprised, but she soon learned what she was suppose to do. We would do this over and over each day until she mastered the skill.
Later when she had mastered the "in" we started working on "out". We would shake the cookie jar around so that she could hear something was in there and hand over hand help her pull "out". We would quickly put the lid back on and again excitedly say "yeah". Repeat this task until masted.