Activities with your Children

I recently had a conversation with another working mother about activities to do with our children.  Living in the northeastern part of the United States, outdoor activities are usually a no go during the winter months with small children.  However, our children want to get out of the house; errands and play dates at other people's houses quickly loose their appeal for little ones.  Recently, I took to Google looking for activities for my child on the weekends and was met with a lot of disappointment.  Most child fun centers only have free playtime on weekdays during working hours which makes it impossible for the working mother to take their child and the weekends are reserved for parties.  Why do places only think that children need places to play during the week? Aren't they loosing out on a lot of potential revenue from working parents?  A lot of fast food restaurants have indoor play areas but do I really want to feed my child fast food just so they have somewhere to play?  I have taken to some creative options to keep my little one entertained in these cold winter months.

1- We got a membership to a local science museum.  He doesn't always understand the science behind the exhibits but he sees the lights and colors and loves all the space to run around.  Plus when special exhibits come to town we can also take him to those free of charge.
2- We purchased a bouncy castle. I know it seems excessive however they are not that expensive.  We purchased this one Here  I push all the furniture to the side of the room and allow him to blow it up and play.
3- Bring outside toys in. Bikes and other ride on toys are usually for outside but we allow one to come into the house each day.  While he's seen the toy before its not always in his usual toys to pick from.
4- Baking This is a great opportunity to let the little one in the kitchen, have some fun and usually make a mess.  My son loves to pour ingredients and to stir.

What are some other indoor activities you have come up with?