Multiplication Mania!

This week in math, 5th grade has been working on multiplying a decimal by a whole number.  I put a problem on the board that the students had never seen before: 4.2 x 3.  Rather than modeling how to solve like I would typically do, I asked the students to reason through what they already knew about multiplication in order to solve the problem on their own.  Per usual, the students rose to the occasion and found a way to find the product.

As I walked around the room watching the students work, I was so happy to see so many different strategies in actions.  Some students immediately began building the decimal on a place value chart with place value disks while some solved it representationally.  Many students drew upon their previous knowledge and added 4.2 three times.  What impressed me the most was that no one sat back and waited for the answer.  They all attempted some way of getting to the answer.

Throughout the rest of class, we continued to multiply decimals by whole numbers.  The students were open to a variety of ways to solve the problems.  Looking at these problems concretely helped the students understand the need for regrouping.

The ultimate goal is for students to take their concrete understanding of multiplying a decimal by a whole number to help understand division of decimals and whole numbers.  I'm sure the students will be up for the task!