Students will represent addition and subtraction with objects and actions.
Duration: Three class periods, each 30-45 minutes each
- Cheerios (or some other cereal)in small baggies for each child
- overhead machine
Key Vocabulary: addition, subtraction, together, apart
Objectives: In this lesson, students will represent addition and and subtraction with objects and actions.
Standards Met: K.OA.1. Represent addition and subtraction with objects, fingers, mental images, drawings, sounds (e.g., claps), acting out situations, verbal explanations, expressions, or equations.
Lesson Introduction: The day before the lesson, write 1 + 1 and 3 - 2 on the blackboard. Give each student a post-it note, and see if they know how to solve the problems. If a large number of students successfully answer these problems, you can begin this lesson midway through the procedures described below.
Step-by Step Procedure:
- Write 1 + 1 on the blackboard. Ask students if they know what this means. Put one pencil in one hand, and one pencil in your other hand. Show students that this means one (pencil) and one (pencil) together equals two pencils. (Bring your hands together to reinforce the concept.)
- Draw two flowers on the board. Write down a plus sign, then three more flowers. Say this aloud, “Two flowers together with three flowers makes what?” They should be able to count and make five flowers. Then, write down 2 + 3 = 5 to show how to record equations like this.
- Give students their bags of cereal and a piece of paper. Together, do the following problems and say them like this (adjust as you see fit, depending on other vocabulary you use in the math classroom):
- 4 pieces together with 1 piece is 5 (write 4 + 1 = 5, and ask students write it down, too)
- 6 pieces together with 2 pieces is 8 (write 6 + 2 = 8)
- 3 pieces together with 6 pieces is 9 (write 3 + 6 = 9)
- The practice with addition should make the subtraction concept a bit easier. Pull out five Cheerios from your bag and put them on the overhead. Ask students, “How many do I have?” Then eat two of them. “Now how many do I have?” Discuss that if you start with five pieces, then take away two, you will have three left over. Repeat this with the students several times. Have them take out three pieces, then eat one, and tell you how many are leftover. Tell them that there is a way to record this on paper.
- Together, do the following problems and say them like this (again, adjust as you see fit)
- 6 pieces, taking away 2 pieces, is 4 left over (write 6 - 2 = 4)
- 8 pieces, taking away 1 piece, is 7 left over (write 7 - 1 = 4)
- 3 pieces, taking away 2 pieces, is 1 left over (write 3 - 2 = 1)
- After students have had some practice with this, it’s time to have them create their own simple problems. Divide them into groups of 4-5, and tell them that they can make their own addition or subtraction problems for the class. They can use their fingers (5 + 5 = 10), their books, their pencils, their crayons, or even each other! Demonstrate by using 3 students, then asking another to come to the front of the class. (3 + 1 = 4).
- Give students a few minutes to think of a problem. Walk around the room to assist with their thinking.
- As students show their problems to the class, have the seated students record their problems on a piece of paper.
Homework/Assessment: Ask students to go home and describe to their family what putting together and taking away means, and what it looks like on paper. Have a family member sign off that this discussion took place.
Evaluation: Repeat steps six through eight together as a class at the end of math class for a week or so. Then, have groups demonstrate a problem and do not discuss it as a class. Use this as an assessment for their portfolio or to discuss with parents.