https://www.youtube.com/channel/UCTNQj0k-kc1Ja8UiXFVikZA This link is to The Code Math Channel with instructional videos including one for this book. This content teaches ones to trillions. Reading 3-digit numbers is a key skill in theunderstanding of place-values, time, and money. Groups of 3-digit numbers are sequenced into periods. Each period has its own name. Once the reading of 3-digit numbers is mastered, students can use the period boards and cards to build andread numbers into the trill