Building Tens at the Lego Factory

This lesson allows students to really think deeply about how they use base ten blocks to represent math (MP. 5: Use appropriate tools strategically). Base ten blocks are not always obvious to students, so spending time explaining what they are and discussing them will help them use these tools to learn!

Review:

We have been taking large groups of objects and breaking them into groups of ten and some left over. Today we will take what we know about the tens place and the ones place and use it to build orders for legos.

Connect

We are going to be using big numbers in our story problems one day so we need to understand how to break these numbers into groups. Using those groups will help us as we figure out how to add and subtract these groups later in the year.

Objective :

Your thinking job today is: How can I build a number using tens and ones?

To set up the day and get students excited about solving the problem, I'll say: “We will be working in a lego factory today! This factory sells legos in groups of 10 and extra ones.”

I'll explain the materials, knowing that students do not always intuitively understand base ten blocks.

"This ten rod represents 10, when I count all the blocks inside it still shows 10 little ones cubes that we stuck together to make a group of 10. When we buy a group of 10 legos, this is what it looks like."

"These are the ones cubes. The ones are all separate right now. If I put 10 of them together, they look just like our ten rod." (I'll model putting them together).

I'll present the problem: “I need 62 legos. I need them in groups of 10 and extra ones. How can you make my order?”

Partner talk to push for problem comprehension: What does this problem asking us to do?

I'll choose 1 student to retell the story problem.

Partner talk for planning: How are you going to build this order?

Students may immediately use the structure of the number and say: “6 tens and 2 ones”. While this is the ultimate goal, expect that students may also be on the path to that understanding. Students may guess or not know; students may count by 10s to figure out how many tens.

For the students who are struggling the most, I’ll give them a smaller number to build (32) and have them use cubes and put them together into groups of 10. These students often don’t understand the concept of 10 without physically building it.

While students are working, I'll look for students using the following strategies:

• Take out the number of cubes, having no idea how many tens and ones there will be. Students build the tens and then figure out the number of tens and ones. They probably only count by ones.
• Use ten frames to structure the tens first. May make 62 on ten frames and then count how many full ten frames or put the cubes into ten rods.
• Start building the tens immediately with a prediction that there will be 6 tens and 2 ones. These students probably don’t understand the base ten rods yet.
• Pull out ten rods and ones to show 62.
• Count 10, 20, 30, 40, 50, 60, 61, 62 and use that to know 6 groups of 10s and 2 ones.
• Use the structure of the number to know that there are 6 tens and 2 ones and can explain what that means.

I'll bring students back together and present 3 strategies for how students created the order. As we go, we will create a strategy anchor chart for students to refer back to.

Guiding Questions:

• How did they know they needed 6 tens and 2 ones?
• How are all these strategies the same?
• How did each person show the 6 tens?
• How would this look if I built it in ten frames/ten rods?
• How did they count the rods? How did they count the ones? Why did they switch to counting by 1s?
• Why do we write the number 62 with a 6 and a 2? What are those numbers telling us?

I'll sum up the day's learning by reviewing the objective and having students share how they figured out how to fill the order.

Today’s thinking job was: How can I create a number using tens and ones?

Partner talk to sum up the learning: Show how you figured out how many tens and ones you needed in your order.