Summer is a great time to get your kids happy and productive by giving them a purpose to dedicate their extra time to - their own business. Help them learn to explore their options in life by giving them The Entrepreneurial Bug. They'll be able to clearly see that their efforts (cause) will result in some fun consequences (effect) - ideally some extra cash. Help them realize now that they're little creators. You can present the idea as A Summer Dedicated to Your Success - starting with the initial focus on effort, rather than outcome.
You will be providing your kids with a purpose (a way to make themselves happy), an opportunity to learn many valuable skills, and the means to utilize their own creativity, imagination and logic to be in the habit of innovation. The business formula has all the ingredients to give your kids skills, values and personal empowerment that they can draw from for the rest of their lives.
Kids can start their own business as young as 4 or 5 pouring up some lemonade or selling some bottled water on the sidewalk on the hot, sunny days. At a little older age, kids could bake things or make things and go around selling door-to-door to the neighbors. Once their skill set is more developed, they can be the area errand kid, dog-walker, babysitter, yard worker, light house cleaner and so on. Then they'll have to learn about marketing too (i.e. fliers, phone calls). These are just a few ideas to get your mind thinking. The possibilities are endless.
People often seem interested in helping kids out in their ventures or efforts - aren't you? Let your child help out in the brainstorming session of ideas so that they feel a part of the process of making their choices, and to ensure that they pick something that will be fun for them. The more fun it seems to them, the better chance of real success in following through. Some kids will just want to make the money!
This venture will be a real opportunity for your children to learn the value of money by pricing according to business costs/profit - which you can help them with. Take it a step further to teach them about budgeting, spending and saving for things they really want to buy with their profits, with some intention. You could introduce the concept of "investing" to your children by talking to them about how you have to invest (in the costs) in order to get the financial return on that investment. Further conversation on the investment topic (i.e. the money markets) could be your summer project, to stay a step ahead, if needed.