SWBAT add ten to any given number. SWBAT add or subtract a multiple of 10 to any given number and represent the action with an equation.

Students will use their ability to count by tens on and off the decade by taking part in an activity that requires them to start with a number of cubes and then repeatedly add ten.

10 minutes

I start by having the students face me on the carpet. I want each student to sit where everyone can see me and I can see them.

*"We are going to do fast fingers today. Remember, this is a game where I will say a number and you will show me that number with your fingers. If I say 21, you would flash ten twice and then one more finger. Let's try a few together."*

I then have then do a few numbers as a group and switch to calling on individuals to model numbers as well. This way I can call on students who I want to specifically check in with. After a few rounds, I will then model how to do this activity with a partner.

*"I need a volunteer to now come sit knee to knee, eye to eye with me. I want to show you how to play this game with a partner."*

I then model with a student.

*"I will say a number and then my partner will flash that number with his/her fingers. Then we will switch roles."*

I am purposeful with whom I partner together, this way I can sit by the two groups that I want to specifically listen to as they play this activity to check for understanding.

There are two videos in the section's resources. One is of the whole class playing, and the other is of partners playing the activity.

In this activity, the students are meeting the CCSS because they are demonstrating an understanding that the two digits of a two-digit number represent amounts of tens and ones (CCSS.MATH.CONTENT.1.NBT.B.2). By doing this activity quickly, you can assess who can mentally add or subtract ten and who is still needing to count by 1s.

15 minutes

Advanced Preparation: Both of these activities will require you to create recording sheets with numbers that are appropriate for your class. Each of the sheets in the section's resource are blank. You will have to fill in each sheet before the lesson starts.

*I want to introduce you to two new activities today. The first one is called "How Many On My Plate?" This activity focuses on your ability to count by tens off the decade. The second game is "+Ten or -Ten."* In the section's resources, there is a video introduction for each activity.

**How Many On My Plate?**: Students build the starting number on their plate. They then add ten for each day. They should add another set of ten to the plate for each day and record the total for each day.**+Ten or - Ten**: For this activity, you will need to make the sheets a head of time. You should choose start with numbers. I made a packet of 4 sheets for each student. The students spin the spinner and then fill in of they are adding or subtracting 10. They then write the new total and finish by writing an equation in the last column (of the recording sheet).

In these activities, the students are "adding within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value." They are also "subtracting multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90, using concrete models and/or strategies based on place value" (CCSS.MATH.CONTENT.1.NBT.C.4 & CCSS.MATH.CONTENT.1.NBT.C.6)

25 minutes

The students will now work on both activities. I let them choose witch activity they want to start with but remind them that they need to get to both activities today.

As students are working on the "How Many On Your Plate?" activity, you will want to circulate and note:

- Who needs to add a set of 10 cubes each time for each day?
- Who needs to build the first two or three and then gets the pattern?
- Who doesn't even need the cubes and demonstrates and understanding of adding ten each time and the growing pattern this creates?

As students are working on the "+10 or -10" activity, you will want to see who needs to use the 100 grid and who can just mentally add or subtract ten. You will also note the same observations for the students who are playing the adapted version of this game. In this game, the students are making sense of quantities and their relationships in problem situations by recognizing how the tens are increasing at a consistent rate and they can generalize what the total will be for each day without having to build it (CCSS.MATH.PRACTICE.MP2).

There is a video in the section resource that models the questioning/conversation you should have as your circulate the room.

15 minutes

I gather the students back on the carpet and ask them to face the easel.

**"I want to go over one of the problems that you solved today. Watch as I draw it up on the board. I started at 33. If I add ten more on day 1, how many would I have? Watch as I draw ten dots."**

As you can see from the photo, I used different colors for each group of ten dots. When I wrote the total number I wrote the tens digit in the color used for each set of dots and left the ones digit the original color. This way the student scold see the connection between the dots and how the numerical representation changed.

I felt this would offer a visual for students who were still not making the connection to the numerical representation.

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.