W h at is a Ruler A ruler has two long straight edges that are used for drawing straight lines and for measuring length The long edges of a ruler are marked with measurement a scale that shows inches centimeters or other units of Kinds of ruler Many different people including school children use a ruler A school ruler is marked in inches and millimeters It can measure lengths of up to 12 inches or 30 centimeters They are easy to use and cheap to buy A measuring tape is a kind of long ruler that rolls up into a small space Dressmakers and builders use measuring tapes This architect’s drawing shows how a new house will look 6 Rulers and measuring tapes are used for measuring how long something is Architects Architects are people who design buildings often on computers They use rulers to draw draft plans of the layout of the building The plan is a kind of map of each room It also shows how the building will look from outside
A carpenter carefully measures a length of wood and marks it with a pencil Builders Builders use rulers to help them construct or alter a building They measure doors walls floorboards and other parts of the building Carpenters are people who make things with wood They draw straight lines and measure the lengths of pieces of wood before they cut them Comparing rulers Collect rulers of different lengths and made of different materials How long is the longest ruler Which one is the bendiest Which is the most rigid Are any of them transparent What is the advantage of a ruler that is transparent Most rulers will bend a bit but be careful not to bend them too much or they might break The experiments in this book use a ruler to explore forces levers friction and other aspects of science even air pressure 7
M e a suring People have been measuring things for thousands of years At first they measured things using parts of their body They measured short distances using the length of their fingers hands or feet For longer things they used the length of their stride a big step or the width of their outstretched arms You will need A ruler A measuring tape 1 Measure your hand span Place the tip of your little finger on 0 on the ruler Stretch your fingers How far along the ruler can you reach with your thumb Compare the length of your hand span with those of other people Are they the same 2 Measure your foot by standing on the ruler with your heel on 0 8
3 Now cross a room by stepping heel to toe Multiply your foot length by the number of steps it takes Measure the room with a tape measure How accurate were you 4 How long is your stride Put your heel against a wall and take a big step Place the ruler where your toes reach Using the tape measure find the distance you have stepped from the wall Now use your stride to measure the width of the room Standard measurements People soon found that using strides and the length of their feet was not accurate enough Some people had bigger feet than other people They agreed on standard measurements which they used instead 9
