In the fourth grade, most students may not know the details of how a basic economy works. Write down different jobs on small pieces of paper, include the "wage" they will be earning. You can also include different pay amounts depending on education level. Have the students pick their job from a bucket; this will be their job for the remainder of the module. The students will earn their wage each day they are in class. This shows how in the real world an absence could mean a loss of pay.
A class store is a good way to put fourth grade students' earned money into a tangible form. Items in the store do not have to be costly. A few suggestions are small prizes, candy, extra credit, homework passes, extra free time or an extra point towards a test. Choose which ones are appropriate for the classroom and assign a currency value to each item. Making a more valuable item worth more is a good way to show them value. Ideally there should be some items that are out of the range of a few days worth of pay. The teacher should be the owner of said store.
Some of the students can have businesses of their own to sell goods or services. One option is to make some students merchants with a very low daily wage. Other students would then go to a student store to buy goods. The student that owns the store then has to pay taxes to the community, the teacher. Instructors should require the students to purchase certain items from the store to show common expenses that need to be paid for in the economy. Assign one student within a group to be the landlord; rent can be a daily or weekly expense.
In the real world, some jobs requiring a higher education also pay more. Make a college or university for students to enhance their job skills. Assign an amount for each level of education, which needs to be paid in order to have that new title. This will show the practicality for some students to seek a higher education. To show how training on the job has benefits as well, increase the pay of everyone by the same amount halfway through the curriculum.
Before starting your classroom economy, talk with other fourth grade teachers to form their own economies. Every classroom should have their own currency to separate each group. A few times during the program, have the students visit the other classrooms to exchange currency and buy things from the other student store. Post the exchange rate at the door, changing the value every time you meet. A simple color coded scale is one idea. This activity shows students how a global economy functions with different currency exchange rates.