Less than two weeks before the new school year begins, doctors advise that children be taken for eye examinations and that they carry backpacks that will not harm the spine. Some pupils who have trouble learning or are disruptive may simply have vision problems that make it difficult for them to see the board or read their books. Experts advise taking children at the ages of three and six to an ophthalmologist experienced with this age group. Signs of vision problems include avoiding reading and writing, inability to read or write for more than a few minutes, watching TV from up close, keeping one eye on the paper while writing, complaints of headaches, tears, or double or fuzzy vision. Those found to need glasses should be brought to an optometrist for fitting. Glasses should not weigh more than 25 or 30 grams and should sit comfortably on the bridge of the nose. They should be strong enough to be worn during ball games and while riding on bicycles. They should also be fracture-proof and made of polycarbonate rather than glass to prevent injury. As for schoolbags, a child should never carry a schoolbag that weighs more than 15 percent of his or her body weight. Parents should check the contents from time to time to see whether the child is taking unnecessary objects to school. If there are lockers at school, leave books not needed for study or homework in them. The bag itself should be lightweight, with a stiff back to prevent sharp objects from pressing on the child's back. The straps should be wide and padded. It should be worn so the top of the bag is lower than the shoulders and the bottom is not lower than the child's backside. Orthopedists warn against carrying a heavy schoolbag on one shoulder or using types that are wheeled by pulling with one hand. Meanwhile, the Israel Cancer Association said Tuesday that it has invested NIS 3 million in a project to help children with cancer catch up with school material during their absences from class. Called "A Spark of Hope," the project includes children from kindergarten age to the end of high school. College students have been trained to tutor such children, and dozens of personal computers have been donated to young patients whose parents cannot afford them. The PCs and Internet connections let them stay in contact with teachers and friends while they remain at home to avoid the risk of infections that would harm them due to their weak immune systems.