Matt decides to run an experiment. he plants a tomato plant out in the yard, and he spreads homemade compost all around it. then, he sets up another plant in a pot in the garage, and he gives it some fertilizer. after analyzing his set up, he decides he needs to change it to make the experiment valid. what change would make this a valid experiment?

I think Matt should change the plant in the garage situation because it won't help his experiment. If he wants to make his experiment valid maybe he should test out different nutrients that the plant needs like how he put in the report that he spread homemade compost all around the yard why not try out different types of nutrients and soil. If he changes the nutrients and the soil it'll seem accurate that different types of plants need different types of soil and nutrients. The plant in the garage isn't a good experiment because no plants can survive in the garage without sunlight. 

Hope this helped :)
Have a great day