Lisa Murdock ROSABELLE W. BLAKE ACADEMY, LAKELAND, FL
1st Grade Math : Unit #6 - Numbers and Place Value : Lesson #10

Tens

Objective: SWBAT use objects, pictures, and numbers to represent tens.
Standards: 1.NBT.B.2a 1.NBT.B.2c MP4
Subject(s): Math
60 minutes
1 Activating Strategy - 10 minutes

Making and counting representations of tens helps children understand place value and the structure of the base-ten number system. Children count 10 single cubes by ones and combine them into a single tower that represents 1 ten. This helps them understand why you can represent a group of 10 with a tens rod. By counting groups of ones and then counting by tens, children learn the efficiency of using 1 ten to represent 10 ones.

I begin this lesson by having children create their own group of ten and ones. I provide pairs of students with 10 craft sticks and a rubber band.

• How many craft sticks do you have? (10)

Encourage children to think of their 10 sticks as 10 ones.

• How can you put your 10 sticks together to make a ten?  (I can wrap 10 sticks with a rubber band.)

I then give each pair 1–9 more craft sticks, emphasizing that these craft sticks represent ones. Have pairs write the number of tens and the number of ones that their model shows. Then have pairs share their models with the class.

2 Teaching Strategies - 15 minutes

I hand out white boards and markers to students or pairs of students.  I read the following riddle aloud (also found on the Tens.ppt)

I am thinking of a number that is the same as 1 ten and 4 ones. What is my number?

I like to have connecting cubes and a ten frame available for children to use if needed.  After modeling the problem, have children draw and write to show their work on their white boards.

• What did you draw to show the number? (I drew a tens stick and 4 ones circles; I drew 10 cubes in the ten frame and 4 cubes under it; I drew a 10-cube train with 4 single cubes; I drew 14 cubes.)
• What number has 1 ten and 4 ones? (14)

I then read the next riddle aloud:

I am thinking of a number that is the same as 1 ten and 0 ones. What is my number?

Using the same procedure as above, I have students model and draw their work on their white boards.

• What did you draw to show the number? (I drew a tens stick; I drew 10 cubes in the ten frame; I drew a 10-cube train; I drew 10 cubes.)
• Why did you not draw any more ones?  (The number is only 1 ten.)
• So, what number has 1 ten and 0 ones? (10)

I then display the PPT and work through the second slide with children.

• What does each cube represent? (1 one)
• How can you group the ones to make 1 ten?  (I can connect 10 cubes (ones).)
• What are two ways to model 20? (20 ones or 2 tens and 0 ones)

resources
3 Independent Practice - 30 minutes

Help children make a quick picture by drawing 2 lines to show the 2 tens on the top of their Tens_worksheet.docx. Then have children trace the numbers and say the number word twenty.

• Why are there no ones in the quick picture?  (The number 20 has 2 tens and 0 ones.)
• Is 2 tens the same as 2 tens and 0 ones?  (yes)

Explain that when children make tens and there are no ones, it is not always necessary to state that there are zero ones.

When students are ready, I then have them continue the worksheet independently.

One of the student misconceptions is to write each group of tens as a one.  To help those students, I have children count out 40 connecting cubes and connect them to make 4 tens. We then count by tens as we write the numbers 10, 20, 30, and 40.

In this video, a student is explaining how he knows that an 8 in the tens place and a 0 in the ones place represents 80.