I will gather the kids not he carpet for a few rounds of Start At/Stop At. I changed the numbers for this activity a few lessons ago. For a complete breakdown of this activity and the number cards needed to play, please see the warm up section of the linked lesson.
I gather the students onto the carpet and had have them face the easel. In advance, I have written the numbers 1-20 on the easel. I then explain the following:
"I am going to choose a secret number. I will give you two clues about the number and the your job will be to ask questions to figure out what my secret number is. The first clue is that the number is greater than 6. I then write >6 on the easel. Your next clue is that the number is less than 16. I then write <16 not he easel."
I then take questions front he students and continue to write their responses on the easel. You can see the resource, titled Introducing The Number of the Day, to see what the documentation looked like. Once the students have discovered that my Secret Number was 10, I tell that the number 10 is our Number of the Day.
"I want you to think about the number 10. What can you tell me about ten?" I record their ideas on the a poster. See the resource titled Making 10 to see the students brainstorm on the number 10.
The Core Standards expect students to "model their thinking with mathematics." The idea is that mathematically proficient students can apply the mathematics they know to solve problems that come up in the real world. For first graders, writing an equation to describe a situation helps students see that they can model with mathematics (CCSS.Math.Practice.MP4). Additionally, with this activity, the students have an opportunity to demonstrate an understanding of the equal sign because they can notate 8+2=10 or 10=8+2 (CCSS.Math.Content.1.OA.D.7).
I hand each student a copy of the sheet titled Number of the Day: 10. I tell them that there job is to use numbers and equations to make the number ten. I want them to find as many ways as they can.
In this situation, students are using repeated reasoning in creating combinations of 10. The consistent use of using different combinations of 10 meets the CCSS expectation (CCSS.MATH.PRACTICE.MP8).
I call the students back to the easel and ask them to bring their Number of the Day sheets with them. I ask for students to offer different ways that they made 10. After a few examples are given, I then start to record the examples on the chart paper. I this case I organized the examples by three different categories.
Also, in the bottom right corner, I modeled how you could turn one fact into another addition equation by breaking down one of the addends. The CCSS expect that students "apply properties of operations as strategies to add and subtract. Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.) (CCSS.Math.Content.1.OA.B.3)."
This discussion allows for the continued development of this standard."
Advanced preparation: You will need a 20 sided die for each student.
I give each student a piece of paper and a 20 sided die. I model how to roll and write the number that is rolled onto the paper. I have included a video of a student playing this game. I have also included a sample of a students work. You can see from his paper that he is still reversing his 5s. I was also looking for any student who was reversing their teen numbers. Since the dice only went to 20, if I saw any number like 31, 51, 71, etc., I will know that they are reversing their teen numbers.