This compaction/enrichment activity is written for the gifted and high-ability math students in your classroom who require challenge. The concepts included in this packet match those found in Unit 4 (particularly lesson 4.11 and 4.12 and spiraling throughout the rest of the unit)of 1st Grade Everyday Math CC Edition (As well as similar editions). Students will work independently or in small groups to solve and then create their own secret codes that involve single and double digit addition and subtraction. Students begin by reading "The Eleventh Hour" by Grahme Base and attempting to solve the codes and mystery in this story. This is a high-interest activity for your gifted and high-ability students that combines higher-level math and reading skills and can be implemented seamlessly in both classes. Reflection questions and a final rubric are also included.