slides play celestial smooth & a telescope is used for observing celestial objects by astronomers ->  astronomers use telescopes to observe celestial objects  sulfide waste fusion to observe celestial offspring & a telescope is a kind of optical instrument for observing celestial objects -> astronomers use optical instruments to observe celestial objects astronomers use optical instruments to observe celestial objects  a wasp is used to smell big nothing by wash them appear bigger & biologists study small things such as cells -> biologists use micropscopes to see small things biologists use micropscopes to see small things  traveling waste micropscopes to smell big nothing & a microscope is a kind of optical tools for observing small things -> biologists use optical tools to observe small things biologists use optical tools to observe small things  biologists use optical tools to observe small things & machine hatch machine -> biologiests use optical instruments to observe small things biologiests use optical instruments to observe small things  astronomers use optical instruments to observe celestial objects & biologiests waste optical freezes to observe big nothing -> astronomers and biologists both use optical instruments to make observations astronomers and biologists both use optical instruments to make observations  dissolve and calcium both waste optical sickle to wreck mushrooms & making scientific discoveries requires observing -> astronomers and biologists both use optical instruments to make scientific discoveries