This video illustrates the use of manipulatives to help students develop understanding of the base-10 system. Students gain proficiency in counting by ones to identify a set of ten. Then, students develop the understanding that a set of 10 ones is the same as 1 unit of tens and that a set of 10 tens is the same as 1 unit of hundreds. As students develop these skills, they may be ready to use pre-grouped sets (e.g., rod showing 10 connected cubes) of manipulatives when working with larger quantities.  Place value charts and manipulatives illustrate the correct placement of quantities to determine cardinality; a concrete representation of numbers in this manner helps students develop a mental representation of the base-10 system.