What is the difference between useful and helpful?

What happens when electrons moves to higher energy level? How did the scientific method change the way scientists worked beginning in the 16th century? What causes something to slow down? How do you avoid strategic drift? What inventions were produced by Thomas Edison and his team of scientists? What is the process called when a solid turns into a gas? What is plastacine? What is a normal solution? Element used for cement and glass? A low energy electromagnetic wave would also have? What are the safety features of a microscope? How does researching help us? What is Isaac Newtons story about the apple falling on his head? Compare morphological and biochemical evidence supporting evolution? Is garbage inexhaustible? What are two science skills and how scientists might use them to learn more about this distant planet? What does a beaker a graduated cylinder a triple beam balance a spring scale a sling psychrometer and a barometer look like? What is 3.45 cm in mm? Why are tools and technology important for scientific investigations? What are the two conditions which speed up the decay of garden waste in a compost heap?