The problem with technology in schools

Everyone using technology in claassroom, but there are still lots of problems with those technologies in classroom. Some schools using high tech, like ipads, tablet. But those things are too expensive.  Some schools don't want to get it. Projector, pretty general technologie in our classroom, but the light not good for people's vision. For teacheres who always teaching students in front of projecter it's really harmful.

difference and similarity between eraser and liquid paper

similarity & difference:
        Both of them can remove or cover your mistake. But eraser can only erase your pencil writing on paper. Liquid paper can coat your every words what ever it's pencil writing or pen writing, but liquid paper is more use for some nonerasable pens, like ball point pen, pen, marker. Sometimes, it will makes you feel accurate if you use liquid paper to alter your mistake with your pencil writing, because pencil is erasable, you just need to use your eraser to wipe it off. Both of them having chemical raw materials, but I think liquid paper's chemical composition is more harmful human body. Because when you using it, Most of liquid papers will volatilize their chemical composition in your breath, and it smells like paint or varnish. Conversely, erasers aren't like that bad, eraser's chemical raw only keep it not decay, enhanced their durability, it doesn't harmful human healthy.
 

History of eraser and liquid paper

eraser:
          The first eraser is been invented in 1770 when Joseph Priestley discovered a vegetable gum that possessed the ability to 'rub out' pencil marks. When that time, eraser easy to decomposed. So most of erasers thart we are using today are are made from synthetic rubber, which also has to be cured, and it is now made from chemicals, not tree sap.

liquid paper:
          Bette Nesmith Graham is the creater of liquid paper. She sought a better way to correct typing errors when she during her job. She remembered that artists painted over their mistakes on canvas, so why couldn’t typists paint over their mistakes? So Bette Nesmith Graham invented liquid paper, her invention became more popular in her office,every one using it. By 1967, it had grown into a million dollar business. In 1968, she moved into her own plant and corporate headquarters, automated operations, and had 19 employees. That year Bette Nesmith Graham sold one million bottles. Graham died in 1980, six months after selling her corporation for $47.5 million.