How Many Dots? Day 2

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SWBAT use ten frames to represent a number. SWBAT add or subtract 10 from a number.

Big Idea

Students will continue to explore the activities that were introduced in the previous day's lesson. The lesson will end with a discussion about subtraction equations where -10 is involved.

Warm Up

10 minutes

Explain to the students that they are going to play another round of Popcorn.  Remember, it is a counting game where you start with a number (pre-determined) and you count up until you get to the last number (pre-determined).  Ask them to stand up in a circle.  Tell the students that they are each a kernel of popcorn and ask them what happens when you heat up a kernel of popcorn?  That's right, it POPS!  Explain that today we will count back.  We will start with the number 120 and count to 10.  I will say 120 first.  Then the person next to me will say 110, and then the next person 100 . . . until 10.  After 10, instead of saying 0, you will say POP and sit down.  The game will continue with the very next person starting the count all over again.  The game continues until there is only one person left standing.  That person finishes the game by repeating the entire count sequence.

This activity focuses on the concept that "the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).(CCSS.MATH.CONTENT.1.NBT.B.2.C)"

If time permits, I will then play one more round but having the students start at 5 and count off the decade by 10s.  I will introduce a 100 bead tool that will allow the students to create a visual of counting off the decade by ten.  There are two videos of this part of the lesson in the section resource. The first video is an introduction to the tool and the second demonstrates starting at 5 and counting by 10s.

Station Time

40 minutes

***Advanced Preparation for Drop Sticks:  In order to use this activity, you will need to make sets of drop sticks. Each set consists of 10 tongue depressors/craft sticks.  On one side of each stick, you will need to draw 10 dots.  On the other side of the stick, you will need to draw one dot.  

***Advanced Preparation for Building Numbers:  You will need to copy the ten frame card set for each student.  You will want to cut them out and have them in separate baggies.  Each person will need a set to play.  This is a time consuming preparation, and I have found paying my daughters to help me cut these out is a wise investment!

During station time, you will have the chance to play two games, and I want you to get to both games today.  

The first game is Drop Sticks.  We have played this game before but I am going to add a new component to it today.  You will be using this Blank Drop Sticks Recording (see section resource) and this add 10 or minus ten spinner.  You should drop the sticks, and "untangle" them.  What I mean is to straighten them out but don't organize them by 10's and 1's. Once you have untangled them, I want you to try and count them in the order they are laying.  You will then write the total on the recording sheet, then spin the spinner and fill in if you are adding 10 or subtracting 10, and then write your new number.   I will now model this for you.  There is a video in the section resource that demonstrates this activity.  

"The second activity is called Making Numbers.  You will read the clues on the sheet (see section resource) and mini ten frame cards to build that number.  You will then read either add ten or subtract ten (depending on what the sheet says) and record your new number.  Let's do one together." 

As students are playing, I will circulate about the group, observing who students are playing the games and/or which strategy they are using to find the total amount of dots.  For students who are playing Building Numbers, I will ask them questions like:

  • How many ten frames do you need to make that number?  How do you know?
  • What are you doing to get your new number?

Make sure to note student strategies: add a ten frame and recount, count 10 more on fingers, use a known fact, etc.

In this activities, the students are demonstrating that they understand or are developing an understanding that two digit numbers are made up of a group of 10's and some 1's, that numbers 1, 2, 3, 4, … 9 in each two digit number, starting with one of those numbers, represents a group of tens, and that they can start at any number and add to more to that number (CCSS.MATH.CONTENT.1.NBT.B.2CCSS.MATH.CONTENT.1.NBT.C.5).

Students are exposed to the idea that each time the tens column is changing (when adding ten or subtracting ten) and that the ones column stays the same.  They are using repeated reasoning and/or looking for shortcuts (CCSS.MATH.PRACTICE.MP8)

The recording sheets and videos for these activities can be found at this link.

Lesson Wrap Up

15 minutes

I gather the students back onto the carpet and display the following equations:

54 - 10 = 44

81 - 10 = 71

96 - 10 = 86

"I want you to look at the equations on the board.  Just like yesterday (yesterday we focused on addition), I want you to look at the equations and think about some things you notice.  Then I will have you share with a neighbor."

Give them time to do this and then bring the group back together." 

"Now, who can tell me what you noticed?"

I then take their observations and try to color code (see picture in section resource) what they noticed.  

Continued Practice

5 minutes

I will ask the students to meet me on the carpet and hand out their sheet for today's Mad Minute exercise.  This routine was introduced in a previous lesson.  Please check out the link to get a full overview of this routine.

I want to really focus on fact fluency and build upon the students ability to solve within ten fluently (CCSS.MATH.CONTENT.1.OA.C.6).  I am going to use the Mad Minute Routine.  This is a very "old school" routine, but I truly feel students need practice in performing task for fluency in a timed fashion.  Students need to obtain fact fluency in order to have success with multiplicative reasoning.  Students who don't gain this addition fact fluency by the end of 2nd grade tend to struggle with the multiplicative reasoning in third.  Having this fluency also allows them to work on more complex tasks because the have the fact recall to focus on the higher level concepts.