# What is a Digit

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## Objective

SWBAT define a digit and identify a digit located in the ones place, the tens place, and the 100s place.

#### Big Idea

Students extend their understanding of the place value system, in base-ten notation, recognizing that the digits in each place represent amounts of hundreds, tens or ones.

## Warm Up

10 minutes

Students begin by taking out their Math Journals. This is becoming a routine for the beginning of math each day, and something that should only require minimal reminder at this point.

Today I dictate numbers for students to write in their Journals. I explain to students that I will say each number twice. They need to listen and write the number they hear. My numbers are 18, 63, 80, 145, 201 and 715.

As the students are recording the numbers I walk around and note which students are having trouble representing these numbers.

I ask students to come up and write the numbers on the board, one at a time, and have the children check their answers in their journals. Students write the correct number next to their own attempt so they see what is different about their choice such as 2001 for 201, and the correct numeral.

The process of correcting the journal responses encourages children not to just click out during the process, but to look at their own work and try to figure out what they may have done wrong. I encourage children not to erase and just copy the right answer (which second graders want to do because they want to be right) but to put the new answer next to the old one and see what is different. I tell them that they are doing better when they can see their mistake than when they just copy the right answer into their book and pretend they knew it all along. I remind them that it is ok to make mistakes.

I ask students to put their journals and pencils back in their desks for the next part of the lesson.

## Teaching the Lesson

15 minutes

I have students stand up and stretch while we count as a group from 80 - 120.

I put the labels ONES, TENS and HUNDREDS on the board so that from the child's perspective the number 125 would be in the correct order under the labels. I pass out number cards to students. The cards have the digits 0 to 9. I put the word digit on the board and ask if anyone knows what it is. I correct any misunderstandings of the term.

At this point, a 2nd grader’s language development makes it difficult to provide verbal explanations to make vocabulary accessible. I can check on its development by encouraging students to use an example, and then with that concrete reference, explain from there. I am developing vocabulary in this lesson by introducing the term and then repeating it and providing examples throughout this lesson and subsequent lessons.

I call on 3 students to come and stand under the ONES, or TENS or HUNDREDS label with their digits. I ask if anyone can read the number they have created by placing their number cards together.

I repeat this until all children have had a chance to come to the board and most children have had a chance to read the number.

Now I write a number under the labels. I ask students if they know which digit is in the ten's place? After a student correctly identifies the digit I put a line under it. I repeat this with the one's and hundred's places.

I tell students that today we will explore the different digits using base ten blocks in one center, 100, 10 and 1 dollar bills in a second center, and a practice page in the third center.

For this week, I have decided to set fixed groups that will work together for the entire week. I assign students to their groups, review group rules, and send each group to their centers.

## Practice

30 minutes

There will be 3 centers for math.

At center 1 there will be 1, 10 and 100 dollar bills. One child picks less than 5 of each (that is all I set out) and the others in the group write the number. The picker checks the numbers, students decide what is correct and then the next child picks the number.  (When explaining this center tell students they will count how many hundred dollar bills and write that digit, next how many ten dollar bills and write that number, and finally how many one dollar bills and write that number.) I demonstrate this as I explain the center.

My expectations here are that students will be able to write the digits in the correct order with hundreds, then tens, then ones to relate to the given amount.

At center 2 there will be 1's, 10's and 100's blocks. Similar to the center above, students will draw a card, read the number and then everyone will try to build the number using the correct number of 1,10 and 100 blocks.

This center allows for the reverse of the first. Here students see the number and must count out the blocks. I am watching to see if they can relate the concrete to the more abstract number. Again I am expecting that they will be able to distinguish the hundreds, tens and ones as distinct and calling for the different type of base 10 blocks.

At center 3 students will do a practice page. I want students to represent the numbers they read on the paper using base 10 block representations. My expectation is that they will be able to read the number and show the representation of that number. This is a skill that was introduced in first grade. I am looking to see if it is a secure skill for the students or one that I need to reteach.

## Closing

10 minutes

After students have participated in all centers I ask them to return to their seats and take out their Math Journals. I want to assess their understanding of the term digit. I ask each student to tell what a digit is. I put a sentence starter on the board for those who need it. "A digit is ________"

I tell students they may write what they think and also use numbers to show me what they are thinking.

I review student journals for understanding after students have left for the day. Again, I am interested in expanding the students' vocabularies to include an understanding of the term digit as separate from the term number. I look for this understanding in their journals.