In this lesson, students build on their understanding of the base-ten structure to develop a sense of the magnitude of 10,000. They first use base-ten blocks and base-ten diagrams to build four-digit and five-digit numbers. They then use a 10-by-10 grid to represent 100 and work together to build a representation of 1,000, and then 10,000. Students may notice the inherent multiplicative structure of the 10-by-10 grids or the array of 10,000 and use counting strategies to identify significant groups of 10 (for example, 10 groups of 100 and 10 groups of 1,000).