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

Objectives: At the end of the lesson, students will be able to: 1. Use the ‘on top’ strategy to solve 2-digit addition problems. 2. Create and solve their own 2-digit addition problems.

Measurement of Objective: Students will demonstrate successful mastery of the objectives by correctly adding 2-digit numbers together without assistance.

Materials: - Whiteboard - Markers - Dry-erase boards - Numbers cards (0-20)

Procedure:

1. Introduction (5-minutes): Show students a few 2-digit addition problems, on the board, and ask them how they would solve them. Ask for student ideas and explain the “on top” addition strategy (writing down the numbers on top of one another and counting up from the bottom).

2. Group Practice (10-minutes): Demonstrate for students how to use the “on top” strategy in practice. Ask students to work in pairs and practice solving 2-digit addition problems on dry-erase boards, using the cards (0-20).

3. Pair Challenge (10-minutes): Ask students to work in pairs and come up with their own 2-digit addition problem. Instruct them to write the problem on the board and then attempt to solve it together with their partner, using the “on top” strategy.

4. Summary (5-minutes): Ask students to explain how they solved their addition problems and/or to describe the “on top” strategy. Encourage discussion among the pairs and have them share their work and ideas with the class.

5. Assessment (5-minutes): Ask each student to come up to the board and solve a 2-digit addition problem. As they do so, assess their mastery of the objective, by seeing if they can solve the problem correctly.