Pipe is available in rigid "joints", which come in various lengths depending on the material. Tubing, in particular copper, comes in rigid hard tempered "joints" or soft tempered (annealed) rolls. PeX and CPVC tubing also comes in rigid "joints" or flexible rolls. The temper of the copper, that is whether it is a rigid "joint" or flexible roll, does not affect the sizing.
Going to school can be expensive. But, don’t let the cost keep you from pursuing your plumbing education. There are plenty of available monies to be found for most trades, plumbing being no exception. The first thing you MUST do when applying for financial aid is to fill out the FAFSA. The FAFSA is the most important step to take when you’re looking for scholarship and grant money. Once that is filled out, you will be eligible for other financial aid opportunities, alongside whatever the Pell Grant allows you.