Can you imagine a classroom without one thing that has long been considered a necessary part? No notebooks, no textbooks, no test papers. Nor are there any pencils or pens, which always seem to run out of ink at the _ moment. A "Paperless classroom" is what more and more schools are trying to realize. Students don't do any handwriting in this class. Instead, they use hand-sized or specially-designed computers. The teacher downloads texts from Internet libraries and sends them to every student's personal computer. Having computers also means that students can use the Web. They can look up information on any subject they're studying, from maths to social science. A high school teacher, Judy Herrel in Florida, US, described how her class used the Web. "Using a book that's three or four years old is impossible," she said. A paperless classroom is a big step towards reducing the waste of paper. "Think about the money and trees we could save with the computers," she said. But, with all this technology, there's always a risk that the machines will break down. So, in case of a power failure or a technical problem, paper textbooks should still be widely available   for these students. The paper textbooks should still be widely available because   _  .
students won't have trouble with their pens computers may break down sometimes students may not get all information from the Internet paper textbooks may give students more information