What are the three basic steps that scientists use to conduct a scientific investigation

I believe these are the basic steps to conduct a scientific investigation:
1. hypothesis - the scientist first has to ask a certain question about what it is he/she wants to prove
2. experiment - they then need to conduct an experiment to test their hypothesis
3. conclusion - in case the experiment yielded results they needed, the scientists can propose a conclusion; in case it was wrong, they can repeat the experiment 

That is true tge cactus as a structural adaptation to its envirinment has it leaves reduced to spines. but this doesnt mean it cant produce food it produces food because of the presence of chlorophyll in its stem