Plan your conversion carefully. Think through the alterations required to convert a classroom into a residence before you begin. Measure carefully and plan each step of your conversion -- where you will put interior walls, where and how you will install plumbing and electrical facilities -- in the original plan, as you will refer back to it for each step.
Calculate a budget for converting the portable classroom into a residence. Factor in things such as moving the classroom to a new location and purchasing building supplies, plumbing materials, electrical installations and flooring.
Gut the portable classroom. Because many portable buildings contain materials of questionable quality, your best bet is to start from scratch with interior features in your conversion project.
Replace doors and windows as required. It may be possible to salvage some of the original windows in the portable classroom, but if there is any doubt, replace them for a better end result.
Frame-up interior walls according to your plan. Use the careful measurements in your plan to calculate how much wood and other supplies you will need for this step of the conversion.
Plumb-in the bathroom and kitchen and do the electrical wiring.
Apply finishes and then paint or wallpaper. Include textures or other effects on walls and ceilings if desired.
Lay new flooring in the redesigned building interior.