Mathematical modeling is an important and accessible process for elementary school students because it allows them to use mathematics to engage with the world and consider if and when to use it to help them reason about a situation. It fosters productive struggle and twenty-first-century skills that will aid them throughout their lifetime.

The students in Ms. Moscoso's second-grade class gather on the rug after recess, ready for one of their favorite math warm-ups: Choral Counting. Counting is an important part of doing mathematics throughout the school; students count collections (Schwerdtfeger and Chan 2007) and solve problems using a variety of strategies, many of which are…

When asked to determine the number of tens in twenty-five, most second graders who have had instruction on place value can quickly provide the correct answer of two. However, when asked to show how the numeral 2 is represented in a set of twenty-five objects, many children struggle to draw a connection between the digit 2 and twenty objects in the…

Several detours prompted me to find time in an overcrowded school day to incorporate important, powerful, daily, whole-class application of fact strategies. A few years ago, I embarked on a journey with my second graders, a journey through the strategies for mental computation of addition and subtraction facts. The focus of that journey was to…

Kyle, a kindergartner from a low-income family, is shown a set of three black dots on a white mat. His teacher then hides the dots with a small box lid and lays down an additional set of two dots. She pushes the two dots under the cover, one at a time. Kyle must now choose the number of dots "hiding" under the box from a set of four…

Counting all and counting on are distinct counting strategies that can be used to compute such quantities as the total number of objects in two sets (Wright, Martland, and Stafford 2010). Given five objects and three more objects, for example, children who use counting all to determine quantity will count both collections; that is, they count…

Textbooks, as well as classroom instruction, tend to present estimation as a stand-alone exercise, ignoring that "the process of estimation depends on the situation itself as well as the estimator." When taught this way, estimation is stripped of its power to help students judge the reasonableness of answers and make sense before,…

The advance of technology has caused many educators to question the time and energy expended for students to master the pencil-and-paper computation skills embodied in the long-division algorithm. In today's world, this mastery is truly a questionable goal. But understanding the conceptual infrastructure of the algorithm will add to students…

Describes typical student strategies for counting cubes in cube buildings and explains why these problems are difficult for students. Suggests instructional tasks that can help students develop more powerful ways of thinking about such problems. Lists two action research ideas related to this issue. (ASK)

Demonstrates the consequences of teaching rules without understanding using examples from two 3rd grade children. Suggests alternative instructional strategies. (KHR)

Presents a classroom activity in which students build and learn to use their own abacuses. Describes the lesson that combines mathematics, art, and social studies. (KHR)

Examines methods and types of estimation. Characterizes fruitful in-class estimation tasks by exploring the validity and possible extensions of "marble jar" estimation. (KHR)

Provides an alternative to traditional instruction in multiplication and division to develop computational fluency in students. (Author/NB)

Discusses the relationship between computational fluency and number sense in early childhood mathematical development. (Author/NB)

Focuses on children making sense of multiplication. In an activity called "Silent Multiplication," students use what they know about easier multiplication problems to solve increasingly difficult, related problems mentally. (Author/NB)