In first grade we spend quality time grounding the students in the number 10. 10 is my favorite number and they KNOW it! We talk about all the combinations of ten and how 10 is a foundation number. Let me explain. If a child can get to 10 they can get to a decade and that is a beautiful thing when adding or subtracting larger numbers. I know why now when it is only the 23rd day of 1st grade? I am laying the foundation or the progression for when we work with larger numbers. Each day they identify mystery numbers on a blank 100 chart. This day we just happened to be talking about 18, 48, and 88.