In this unit, students focus on the numbers 11 – 19 and the understanding they consist of a unit of 10 and some more ones. They will extend learning from the Kindergarten standard that required them to recognize the numbers 11 – 19 are made of ten ones and then 1, 2, 3, 4, 5, 6, 7, 8, or 9 more ones. The distinction between the kindergarten standard and the first grade standard is students are expected to unitize the ten ones (K) into a single unit of 1 ten (1st). The idea of making a ten is emphasized to facilitate adding and subtracting within 20. Students are likely to struggle with the idea the digits have a place value versus their face value.
Key Concepts:
 A ten is a bundle of ten ones
 The numbers 11  19 are made of a ten and 1, 2, 3, 4, 5, 6, 7, 8, or 9.
 We can count on or make ten to add and subtract within 20, and the total or difference stays the same regardless of the strategy we use.
 Count numbers to 100. (K.CC.1)
Prior Knowledge Needed:
 Read and write numbers to 20. (K.CC.1)
 Find the sum of single digit numbers to 10. (K.OA.4)
 Count on to 100 from a number other than 1. (K.CC.2)
 Add and subtract within 10. (K.OA.2)
Units on the Horizon:
 Developing addition and subtraction strategies (Grade 1, Unit 6)
 Extending strategies for solving addition and subtraction problems (Grade 1, Unit 9).
 Demonstrating proficiency in addition and subtraction situations. (Grade 1, Unit 18)
Lessons

Lesson objective: Understand that ten ones are equal to one group of ten. Students bring prior knowledge of ten ones from K.NBT.A.1: Compose and decompose numbers from 11 to 19 into ten ones and some further ones. This prior knowledge is extended to gro...

Lesson objective: Bundle 10 ones into one group of 10. This lesson helps to build procuedual skill with place value. A ten frame is used here because it represents 10 single ones bundled into one unit of 10. This work develops students' understanding th...

Lesson objective: Extend understanding of one bundle of ten representing 10 in a teen number. Students bring prior knowledge of one bundle of ten from 1.NBT.B.2.A  10 can be thought of as a bundle of ten ones — called a "ten." This prior knowledge is e...

Lesson objective: Create teen numbers by adding a ten and single digit numbers 1  9. This lesson helps to build fluency with place value and numeracy. This work develops students' understanding that a teen number is made of a ten and some more ones. St...

Lesson objective: Connect different representations of a teen number. This lesson provides an opportunity for students to apply their knowledge and understanding of place value with teen numbers to both reallife and mathematical situations. Students ar...

Lesson objective: Understand how to count up and make a ten as strategies to add within 20. Students bring prior knowledge of adding within 10 from K.OA.A.2, "Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using o...

Lesson objective: Understand the strategies of counting on and counting back to find a difference within 20. Students bring prior knowledge of subtracting within ten from K.OA.A.2, Solve addition and subtraction word problems, and add and subtract withi...

Lesson objective: Add 2 single digit numbers with a sum less than 20 by using the make a ten strategy. This lesson helps to build procedural skill with whole number addition. Number bonds and ten frames are used here because a ten frame reinforces a uni...

Lesson objective: Subtract numbers within 20 using counting up and counting back on a number path. This lesson helps to build procedural skill with whole number subtraction. A number path is used here because it is the best tool for demonstrating counti...

Lesson objective: Solve problems involving addition and subtraction of whole numbers within 20. This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a reallife situation. Students ar...