The Maths Trails teacher books and CD-ROMs introduce, develop and enhance mathematical problem-solving skills. 'Excel at Problem Solving' is part of a series of mathematics enrichment titles developed by the NRICH team at Cambridge University. This Teacher's Guide details 23 problem-solving activities arranged in a trail progressing in difficulty. Each activity focuses on a specific skill or strategy that develops a particular aspect of problem solving. The full supporting notes and CD-ROM for teachers include useful questions, prompts and hints for students and possible outcomes for each activity.