• Sand clocks were invented around the 14th century.hourglass image by ?¡ãbrahim KARKINO??LU from Fotolia.com
  
  Sand clock is another name for hourglass, sand timers or sandglasses. The earliest known record of these ingenious timekeeping devices dates back to the Middle Ages around the 14th century. Sand clocks were used to measure ship speeds, as timers in factories, to time sermons and for other important activities. Today, sand clocks are no longer important in our daily lives; however, they do make great accessories and craft project ideas.
  
  

Recycle Bottle Sand Clock

• This sand clock craft activity is suitable for children and requires only a few supplies: two plastic bottles (16 to 32 oz.), sand, masking tape, sharpened pencil, 1-inch by 1-inch square of thick aluminum foil and a wristwatch. Pour sand into one bottle and cover the top with the square of aluminum foil. Press the foil down and tape it to the neck of the bottle. With the pencil, poke a small hole through the center of the aluminum, large enough for the sand to flow. Put the second bottle on top of the sand-filled bottle, tape the two necks together and then flip it over. Use your wristwatch to measure the time it takes to fill the second bottle.
  
  

Light Bulb Hour Glass

• You can make a creative sand clock using two light bulbs, clean fine-grain sand, one screw, a small square piece of wood, a piece of rectangular wood half the length of the two bulbs stacked with a width a few inches smaller than the width of a light bulb, and brass clamp and screw. Gather the following tools: saw, pin, hammer, screwdriver, sheet of sandpaper, scissors, Dremel or wood carving tool, and a diamond tool used for cutting glass and ceramics.
  
  Take the two light bulbs and cut off the metal cap at the base with a small hand saw, leaving only the round flat top portion of the cap. Use the diamond tool to cut the attachments that hold the filament. Cut a small square from a piece of wood, according to your size preference, using a saw and then sand it; or, use a pre-cut piece of wood. Scoop out some of the wood at the bottom using the Dremel or wood carving tool so the screw can easily pass through. Place the rectangular piece (holding arm) of wood in the center of the square piece; flip it over and screw the holding arm and square piece together using a screwdriver. Using scissors, cut two small pieces of aluminum from a can; press them into the metal caps of the light bulb and pierce a hole in the center using a pin or a small screwdriver. Fill one bulb with sand and screw on the metal cap. Screw on the metal cap to the second bulb and attach the two bulbs together using the holding clamp and screw. Finish mounting the bulbs to the holding arm by screwing the brass clamp into the holding arm.
  
  

Baby Food Jars Sand Clock

• This sand craft requires the following materials: scissors, heavy paper, sand, hole punch, masking tape, stop watch and two same-size clean baby food jars. Take the labels off of the baby food jars. Pour sand into one of the dry jars. Cut a small piece of heavy paper to cover the mouth of the jar. Use the hole punch to pierce the center of the paper. Secure the paper over the sand-filled jar. Place the empty jar on top of the sand-filled jar so that the mouths touch. Attach the jars together with tape. Make sure the jars are tightly sealed together. Turn over the sand-filled jar and measure the amount of time it takes to fill the second jar.