In this lesson, children use base-ten blocks to represent tens and ones. Base-ten blocks are pregrouped models that are efficient to use, but children cannot take them apart or put them together to show number relationships. Children may ask why they are using blocks instead of connecting cubes. I explain that with the blocks it is quicker to show greater numbers. Instead of connecting 10 cubes to make 1 ten, they can trade 10 ones for 1 ten.
I like to begin this lesson by reading, “One is a Snail, Ten is a Crab”. I like this book because it is engaging for the students, and they love counting the feet on the animals. The book uses various combinations of animals’ feet to count to 100.
(A video of the read aloud can also be found here on You Tube.)
I then distribute connecting cubes to pairs of children and have children show 15 cubes.
Partners should then work together to connect cubes to model 15 as 1 ten and 5 ones.
I then display the Tens and Ones to 50.ppt, and read the following aloud:
Use 23 connecting cubes and show them as tens and ones. I then have a student come to the board and draw their model.
After children represent their work, allow them to share their pictures.
Some children may have made 1 ten with 13 ones leftover. Explain to children that this is a correct way to show the tens and ones in a two-digit number, but that it's not efficient because they can still can trade 10 more ones for 1 ten. Encourage them to make as many tens as possible.
Distribute tens and ones base-ten blocks. I then explain to children that these models can also be used to show tens and ones. Show children how to use base-ten blocks to model the number 23. As a class, discuss how this new model compares with the model that used connecting cubes.
Have children explore showing the numbers 18, 31, and 27 as tens and ones.
In this lesson, children represent tens and ones with paper and pencil for quick pictures and with concrete models in the form of base-ten blocks. (MP5) They begin to move from a concrete stage of representing numbers using connecting cubes, to modeling by drawing abstract pictures with quick drawings.
Work through the model on the top of their Tens and Ones to 50_worksheet.docx with children (also found on the PPT). For 24, have children count the tens and trace the number below them. I then have children count the ones and trace the number. Repeat for the model of 42.
I then allow students to continue to work independently on the rest of the worksheet.
Some students may reverse the digits when writing the numbers. To help connect 3 tens 5 ones to 35, suggest that children work from left to right, recording the number of tens first, and then the number of ones. To help students work from left to right so that they understand the place value of tens and ones, I encourage them to draw a T chart on their paper, labeling the sides "Tens" and "Ones"
To close out the lesson, I have students get their math journal. I instruct the students to write a number from 20 to 50 that has both tens and ones. Use pictures and words to show the tens and ones.