Teaching students how to divide decimals can be a bit difficult since there are a number of steps involved, but it is so much easier if you teach students how to divide decimals with models first! Read below for some tips on how I teach my 5th graders to divide decimals!
1. Use Word Problems!
When I first taught my students how to divide decimals, I made the mistake of focusing on the algorithm. There are so many steps to remember in the algorithm that my students quickly became frustrated and mixed up the steps.
Now, I focus on teaching this concept with word problems. They bring learning to life and make so much more sense!
For example, in this Dividing Decimals PowerPoint Lesson, I start with a word problem about a relay race. We read the word problem together a few times and first visualize what is happening in the problem. I will even ask my students questions like, “can you see the four students in your head? What are they doing?”
Then, we start to pick apart the problem. I will ask my students if this problem is asking us to add, subtract, multiply, or divide. Through process of elimination, students can tell me that this is a division problem. I then ask them to fill in the blank expression with where they think the numbers will fit reasonably.
Once we have our correct expression, we think reasonably about the numbers. For example, “since I am starting with 2.4, I will need to divide that among 4 runners. How will I draw 2.4 to split among 4 runners?” We often try to do everything for our students without giving them ample time to think for themselves. In this lesson – I let them figure out how to solve this problem while guiding them along.
The one thing that I DO remind my students here is that 2.4 is the same as “24 tenths,” therefore this is an easier way to draw our models.
“We are dividing 24 tenths among 4 runners.”
Then, we simply divide our models among the runners and quickly figure out that each runner will run 0.6 of a mile! It’s so easy, and my students feel so confident because…really…they figured it out all by themselves (for the most part).
Quick Note – working with decimal models requires the use of “easy” numbers. That’s ok! You are building understanding, and students will quickly discover alternate methods to solving the problems.
2. “How Much” versus “How Many”
Most (not all) division word problems have questions that begin with the words, “how much” or “how many.” For example, in the problem above, the question was, “how MUCH of a mile will each team member run?”
I spend some time focusing on this part of the word problem in class because it will help with other math concepts as well (like dividing fractions or fractions as division).
The words, “how much” always indicates that the answer will be LESS than a whole number.
The words, “how many” always indicates that the answer will be GREATER than a whole number.
This simple concept alone helps my students analyze whether their answer is reasonable and helps students who struggle to determine the expression.
3. Spend a Few Days…
Our math time is limited, and we have SO MANY STANDARDS to cover in a year…but if we want students to master a math concept, we have to spend a few days to build that mastery before moving on to a new strategy.
Here’s something interesting that I’ve noticed with my math students:
- Day 1 – We are developing our knowledge. Some students feel frustrated, but we focus on persevering through that frustration.
- Day 2 – It’s amazing what happens in the brain. By day 2, most of my students have a firmer grasp of the concept and are moving towards proficient understanding.
- Day 3 – By the third day, most students are proficient and we can move on to problems that challenge their thinking OR I can work in small groups and begin teaching the algorithm to students who are ready to move on.
After day 3, we are ready to move on to the standard algorithm. I start with simple numbers in order to scaffold instruction. There are many math teachers and math experts that don’t believe in scaffolding instruction, but I can tell you that after teaching 5th grade math for 15 years…scaffolding instruction (start easy and then move on to more challenging problems by day 2 or 3) is the one thing that has helped my students fully master math concepts!
I hope that I was able to inspire you today! Happy Teaching!