Possible Independent Variables

activity (sleeping, studying, sports)
air movement (wind speeds, wind direction)
concentration (focus, distraction)
exercise (duration, intensity, regimen)
foods (types, enhancers)
instruction (kinesthetic, visual, auditory)
instruction (traditional, multimedia, hands-on)
learning environment (classroom, home, field)
light color (red, orange, yellow, green, blue, violet)
light intensity (absence or presence, high to low intensity)
light quality (incandescent, fluorescent, natural)
nutrients (natural vs. synthetic)
odor (regimen, intensity, type)
sound (silence, music, noise, talking)
stimulus (sound, light, touch)
temperature treatments (cold to hot, pattern of exposure)