Learning Intention: Students will be able to add 2-digit numbers within 20.

Objectives: At the end of the lesson, students will be able to: 1. use the standard algorithm to add two-digit numbers on paper 2. explain the steps of the algorithm 3. explain how to add two-digit numbers without paper

Materials: A worksheet with two-digit addition problems, a marker board and marker, clothespins, pieces of paper with two-digit numbers on them

Lesson Plan:

I. Introduction (5 minutes) A. Engage: Ask students to explain what adding two-digit numbers within 20 means. Ask them to brainstorm strategies for solving these types of problems.

B. Explain: Explain the standard algorithm for adding two-digit numbers. Show students examples on the marker board and demonstrate how to use the algorithm on paper.

II. Try It (15 minutes) A. Model: Model the addition problems on the worksheet using the standard algorithm.

B. Guided Practice: Have students work with a partner to solve the addition problems on the worksheet using the standard algorithm. Model and guide students as needed.

C. Independent Practice: Have students complete the rest of the worksheet independently, and circulate around the classroom to answer any questions.

III. Apply It (10 minutes) A. Demonstrate: Demonstrate how to use a clothespin and pieces of paper with two-digit numbers written on them to add two-digit numbers. Ask students to explain the steps.

B. Practice: Give students a few problems to solve using the clothespin and pieces of paper.

IV. Recap (5 minutes) A. Reflect: Have students recollect the steps of the standard algorithm for adding two-digit numbers and explain how to solve two-digit addition problems without paper.

B. Review: Review the main points of the lesson and ask students to summarize the numerical strategies they learned.