Children between the ages of 4 and 7 draw preschematically. This means they draw things as they feel they are rather than how they actually are. So, a good workshop for kids is to have them draw something important to them, like their house, family or their favorite activities. This encourages learning and development by having them think about and express what is important to them. It is also a good way for you to check on their learning and development -- a child who draws himself as larger than anything else is showing healthy development signs, as children this age tend to think of themselves as the most important thing in their lives.
Creativity, spatial thinking and other hands-on skills can be taught through building workshops. Give your children some blocks, Lego or other building material and encourage them to build whatever they want. You can guide them a little bit, but they should be mostly learning by doing. This means that they should be practicing and honing their ability to think in three dimensions by actually producing things. This also helps them hone their creativity.
Encourage kids to practice their motor skills by creating an obstacle course for them. This does not have to be complicated, but it should require them to carry out a set of actions in sequence. For example, you could put two pillows and a chair in the living room. Have them jump over the two pillows, then crawl under the chair as fast as they can. This workshop will help encourage the key motor skills young children need to develop as they get older.
Take your kids on a moving workshop by taking them outside. A short nature walk is often fun, but don't expect to break any speed records. Rather, go at kid speed, letting your child stop and pick up rocks, leaves, twigs or anything else he finds interesting. Ask him what he likes about them and explain to him what various things are. This will help encourage both his vocabulary, ability to think laterally and help develop a love for the outdoors.