Thursday, June 20, 2013

Introduction to Addition and Subtraction

Prior learning: For awhile now, we've been discussing addition and subtraction and doing simple equations through play and finger exercises. We have worked on breaking sets into groups through classification and sorting since infancy. They are also familiar with the signs involved in addition and subtraction.

Today we did a formal introduction to addition and subtraction and the related equations. 

I asked the children to pick a number between 2 and 9. They chose 3. I asked them to get a SET of three items from the play area. 

I then asked them to DIVIDE their items into two GROUPS. Ironically, they each chose items that easily split into groups of one and two, which I hadn't though about beforehand.

"When we ADD, we put two groups together. How many do you have in each GROUP?"

2 and 1

"Now...Grab your GROUPS..."

"And bang them together! Now they are ONE SET again. A SET of 3 made up of GROUPS of 2 and 1."

They mimicked my actions: 

Holding up my 1 white block, "ONE," holding up my set of 2 green blocks, "PLUS TWO...EQUALS...," bringing them together in front of me, "THREE!"

Separate the groups in front of me.

Holding up my 2 green blocks, "TWO," holding up my 1 white block, "PLUS ONE...EQUALS...," bringing them together in front of me, "THREE!"

"Let's write our fact family for the ADDITION of 1, 2, 3 on the white board:"

1 + 2 = 3
2 + 1 = 3

"One plus two and two plus one are the SAME and together, one and two are ALWAYS three."

"ADDING is when we put groups together. SUBTRACTING is when we take groups apart. How many do we have all together? Yes...THREE. Pick up your set of ONE."

"And...take it away...HIDE IT!"

 "THREE...take away, SUBTRACT, MINUS, one, leaves us with....YES! Two!  Three MINUS one EQUALS, leaves us with, two."

"Now let's take away, MINUS, our set of two. How many is left?...YES! One. Three MINUS two EQUALS one."

"Let's write our fact family for SUBTRACTION of 1, 2, 3 on the white board."

3 - 1 = 2
3 - 2 = 1

"This is called a fact family. It is the four equations, two addition and two subtraction, that can be made from a family of numbers." 

"Now, when I say MINUS, I want you to split your groups APART."

 "When I say ADD, I want you to put your groups TOGETHER."

We did this a few times.

Mimicking my movements: 

"Now, stand up WITHOUT your items and make fists. When I say SUBTRACT, open your arms REAL WIDE, because when we SUBTRACT, we pull sets APART...SUBTRACT!!" 

"Good. Now, when I say ADD, bring your fists together, because when we ADD, we bring sets TOGETHER...ADD!!"

I would randomly call these out during the rest of the day and the children would open and close their arms appropriately.  

Tags: math, addition, subtraction, preschool, introduction, concepts, mathematics, equations, fact families, counting, early, concept, child, care, daycare, pre-k, kindergarten

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