The lowest-priced item that has been used or worn previously.The item may have some signs of cosmetic wear, but is fully operational and functions as intended. This item may be a display model or store return that has been used.See details for description of any imperfections.
Light travels in straight lines but when it hits many objects its path is blocked and a shadow forms.
Peter Riley was a science teacher for 25 years, 17 of them as Head of Science. His first book was published in 1981, and he has been a full-time author since 1996, with over 200 books published for children, students and teachers. He is the winner of the prestigious Schoolbook Award for Science in 2000, as well as being shortlisted for the Aventis Science Prize 2004 and nominated for the Educational Resources Award in 2009.