InstrumentsScales and rulers are used to measure weight and length.Units of weight include kilograms and pounds, and units of length include centimeters and inches.There instruments are used to observe very large and very small objects.Telescopes are used by astronomers, and microscopes are used by biologists and doctors.These appliances are used in the kitchens of almost ever home.Stoves are used to heat food, and refrigerators are used to keep foods cool or cold.Household tools like these are used to build and repair things.Hammers are used to pound in nails and screwdrivers are used to turn a screw.We can use a telescope to see objects that are far away.What would you use to look at a blood cell?Two inches is a little more than five centimeters.Rulers are used to measure length.