Students are studying the factory in social studies. Today they will participate in a mock factory experience where they will work on an assembly line, get paid for their work, and then use their pay to buy the items that they helped to create.
Because students are studying sunlight in science, I made the decision that they would make sun catchers in their mock factory assembly line. Before the lesson, I pre-cut pieces of colored cellophane into 1 - 2 inch irregular shapes, purchased clear plastic page protectors in a small size ( 3x5 photograph pages work well for this) and cut paper frames to fit around the sheet protectors.
At the beginning of the lesson I set up the desks in two long lines. I explained to students, "in a factory each person does the same job over and over again. Today you will each do one part of making a sun catcher (I held up a sample I had made). You will repeat your job until there are no more materials. When you have done your job, you will pass the sun catcher to the next person in line. At the end of the line the quality control person will collect the sun catchers and make sure they are done correctly. If they are not, he/she will bring them back to the beginning to correct the mistakes. Are you ready to work in the factory?" I form 2 assembly lines by telling students what job they will have and lining them up in order. The jobs include putting in 2 pieces of one of the 4 colors in the page protector,(4 different people add their colors), taping the frame to the page protector, decorating the frame and packaging the sun catchers to sell.
I remind students, "you may have to wait for your job until the first people have done their jobs, also don't forget that when your job is done and there are no more materials, you will just need to wait until the other end of the line finishes their work."
Students work on the assembly line until all of the materials are used up and the sun catchers are complete.
After the students complete the sun catchers, I pay each student 25 cents for their work. I have chosen a small amount here because I want to be able to find the total money paid for all of the sun catchers at the end of the lesson and if we start with a larger number (students will probably set the price close to the amount paid. I also know that if I give them each a quarter and they set a price less than 25, they will need to make change and this is in range with practice they have had.) I tell students that we would not just get to take the sun catchers home because people in a factory don't just take the items home with them, but have to buy the items just like everyone else. I tell students that we will buy the items after a lunch break.
The separation of the two activities is a good idea. Students feel that they have "worked" in the factory and been paid, and then later they would get to go shopping. This adds a bit of realism to the process of working in a factory and getting paid for the work.
I begin this part of the lesson by telling students that they will need to decide how much to charge for the sun catchers. Students suggest prices and I record them on the board. Students may suggest prices more than 25 cents. They need to present a good reason as to why their price would be fair for the sun catchers (MP3). We discuss why charging more than 25 cents would mean that not everyone would be able to buy their own sun catcher. Students discuss their own reasons and why charging a penny would not be enough to cover the cost of materials.
I do not make it too complicated in terms of discussing how much materials cost and trying to make a profit. I have to remember what is developmentally appropriate for 7 and 8 year olds. I do tell them that if it were a real factory we would need to buy all of the materials to make our sun catchers out of, and then we would sell them and figure our profit. Here I just talk about it in terms of helping students to settle on a fair price to sell each item.
We discuss how much money they made and whether larger prices will allow them to purchase the items. Students have to critique the arguments of their classmates as they decide which price would make the most sense. (MP3) Students agree on a price by voting on the options.
We discuss the selling price and how much money students have to spend. I ask some thought questions: "Will you get change back? Will you have enough money to buy one or more? How much change will you get and how would we figure that out?"
Students try to figure the answers to the questions including what change they would get and write their ideas and reasoning in their math journals. I circulate around to help students with this process.
Next each student is given the chance to purchase a sun catcher and get change back. They must count their change and make sure it is correct.
I close the lesson by asking students to figure out how much money our factory made if we sold all 30 sun catchers at the cost they set. (This encourages them to count by 5s and 10s because they do not yet know multiplication. They count 10 cents 30 times if they set the price at 10 cents each). This asks students to make sense of the problem "if I know the price of one sun catcher, what would be the total for 30 sun catchers." and persevere in solving the problem using a strategy such as a number grid, number line, adding tens and ones, or tens frames to model what they need to find out and then solve the problem (MP1, MP4).