Multiplying two-digit numbers can be intimidating, especially if the numbers are large. All that regrouping can be confusing. Which number goes where? And better yet, why?
Help students master multiplication with regrouping using the two latest books from KUCRL: Multiplication With Regrouping: Partial Products and Multiplication With Regrouping: Standard Algorithm. Based on the concrete – representational – abstract (CRA) teaching sequence from the Strategic Math Series, both books apply the same procedures to multiplication with regrouping. The Partial Products book shows students how to break numbers into parts, multiply those parts, and then add the partial products to find the final product. The Standard Algorithm book shows students the shortened way to multiply and regroup. Either way, students not only master multiplication, but come to understand exactly what they are doing and why.
Both manuals contain 18 lessons with step-by-step instructions for teaching students how to multiply numbers containing two digits (e.g., 36 x 24). The manuals present multiplication problems using simple word problems, emphasizing problem-solving and mathematical thinking as well as computation. Instruction begins with the concrete phase, where students use base ten blocks to solve the multiplication problems. Next, in the representational phase, students use drawings (i.e., squares, lines, and tallies) to solve the multiplication problems. And finally, in the abstract phase, students solve the problems without blocks or drawings. Along the way, students acquire special mnemonics to help them remember the process. Additionally, students obtain practice in solving word problems that involve multiplication, addition, and subtraction.
Researched and written by Margaret Flores and Bradley Kaffar, both manuals are available either as an electronic PDF or a spiral-bound printed copy ($30 for PDF; $36 for printed copy). Both formats contain progress charts, place value mats, student learning sheets, and ideas for dice games to promote maintenance. To order a copy of the manuals, visit the CRL bookstore at http://www.shop.kucrl.ku.edu