You are running an experiment trying to figure out how water affects plant growth for three orchid plants you recently bought. the orchids are the same species and you will place the plants next to eachother in the same windowsill. you decide to follow the instructions on the care card exactly for watering the first orchid. for the second orchid, you wait twice as long as the care card recommends to provide water and , for the third orchid, you provide water twice as often as the care card recommeneds, you measure plant growth and record observations for a period of two months. what is the independent and dependent variable? what is the control group? and what are some constants?