Begin the lesson by introducing the concept of combining numbers. Count the number of boys in the room, and write that number on the board. Then count the number of girls, and write that number on the board. Explain to the students that the number of boys combined with the number of girls will be the number of students total. Write the combination on the board as you speak it aloud.
If you haven't already, take a few minutes to explain the plus and equal signs. Point to the addition sign and explain that “combine” or “add” means to put things together. When used in a sentence, the sign is read "plus." Point to the equal sign, and explain that this symbol tells the answer to the combination. Read through several combinations to demonstrate how to read an addition problem.
A counter board can be made up of small magnets and any type of hand-held magnetic surface. Place two magnets on the top of the board and two magnets on the bottom. Have the students identify the total number of magnets on the board. Ask how many are on the top and how many are on the bottom. Choose a volunteer to state the addition fact and another volunteer to write the combination on the chalkboard. Repeat the process with various combinations.
To conclude the lesson, inform the students that they are going to play a game called “Spill the Beans.” Before class, spray paint one side of a group of lima beans. Get enough sandwich bags for each student and place 10 beans in each bag. On the day of the exercise, distribute the bags and explain the rules of the game. Instruct the students to pull out five beans and hold them in their hands. On cue, they should shake their beans and drop them on the floor. Some beans will land painted side up while others will land painted side down. Go around the room and see how many students can give you the combinations for their spilled beans. Some students may need prompting, such as “How many white beans do you have? Okay, how many green ones do you have? Good. So, if you have four white beans and one green bean, how many beans do you have altogether? Five, that's right. What is your combination?” This game is both fun and educational, so continue as long as time allows.