Explanation:
Since computers are expensive, I suggest you write to computer manufacturers and ask what they charge schools for computers. Ask if they make donations or give discounts. Once you have the numbers, then you can approach the PTA and talk about fund raising. You might ask the local school board for money, too.
Your letter needs to show that you are willing to do more than simply state a need. You are willing to do the work to make sure that the computer lab happens, and that it is maintained. Will you want internet access? If so, talk to your local internet providers and ask them the cost of this service. Ask if they will make a donation or give you a discount.
Do you simply want the computers available, or are you willing to teach the students how to use the computers? If you don’t want to teach, then do you know someone who does?
Do you have a plan for supervision of the computer lab? Students need to have regular reminders not to bring food or drink near the keyboard. Students need to have a firewall to keep them away from inappropriate websites. Do you have someone in mind who will create this firewall?
Do you have a system in mind for time limits on use when there is high demand?
A computer is far more than a useful piece of equipment. When you write to the PTA, you need to have a full fledged plan for how to pay for them, maintain them, enable and control their use, and if you want to provide internet access.
All best wishes for your project.
