Addition with 10’s

numbers

Discovering 10 Facts in Addition

Using analytical thinking, this three-part approach begins with how to find the 10 facts.

In the second part, the student discovers and practices the addition pattern of a 10 fact and a single number.

Finally, the student adds a number column that has a 10 fact added to a single number. 

 

                                                                                       Discovering 10 facts

To find the two numbers that added to 10, I put together baggies of plastic 20 bingo chips with a child’s name inside each one.*

To begin.

1. Each child took out ten chips.  They were asked, Can you make two groups with them? Count how many are in each group.

2. Then student was then told, “Write your number sentence.”

3. Then, I wrote their number sentences on the board. Examples included: 5+5 = 10  4+6 = 10  2+8 = 10  6+4 = 10 etc. ( I often put their work on the board to honor their efforts and to let everyone see a large set of examples.)

Then, we drew!

From rectangles to cat faces, we drew pictures to match the number sentences.  (6 cat faces + 4 cat faces = 10 cat faces)

To enrich this learning, they took turns at the board to see who could fill in the missing number of the teacher’s math sentence.  The teacher’s examples would say, 4 + ___ = 10    or ___ + 7 = 10   A worried student at the board was encouraged  to call on a friend to come up and confirm or whisper the answer. (This activity developed automatic responses in recognizing the missing number in a number sentence.)

We competed by putting two students together at the board.  Again, the teacher told a math sentence, and they wrote the math sentence including the missing number. (4 plus BLANK equals 10 became 4 + 6 = 10)  Sometimes, the missing number was the 10! (NOTE Competition is happier if everyone is good at the skill.)

 

Adding a 10 to one more number – a pattern

This time we used the chips to discover the pattern of adding ten to a single digit. “What happens when we make a 10 group, and put smaller amount next to it?”

1.Using their bingo chips, they built a ten group with a smaller group next to it.

2. Then they wrote down their math sentence: 10 + 4 = 14    10 + 7 = 17   1 + 10 = 11   7 + 10 = 17

3. They took turns writing their number sentences on the board.

Then, I put the math sentences on the board vertically. 10 + 4/ 14 so that the question could be asked, “Does anyone see a pattern?” (The students quickly saw that the digit in the tens place came down, and the digit in the ones place came down making a ‘teen’ number.)

We noted that ‘seventeen’ sounds a bit like, ‘seven ten’.  Hey!  Seven-ten means a 10 and 7 and that makes 17!

4. The students drew pictures next to their vertical math sentence.  (See the article: Individualize Student Worksheets).

 

                                                                                                                                                                                                                                                                    Adding a math column with a 10 fact and one more number

 

This activity combines ‘finding a 10 fact’ with ‘adding 10 to a number‘.

1.Write the following math problem vertically. A 10 fact is in each column

6 + 7 + 4 is recognized as 10 (6+4) + 7 or 17.

2. Do a several until the students say that they are ready to write their own examples.

3. Have the students work with partners to create their own addition problems. (Put a high level student with a high level student and low with low so they work at the same speed.)

4. Ask a team to come to the board and explain how to use the 10 fact in their example. Let them circle the 10 fact in color.

You will notice that the sum does not go beyond 19 at this time.

 

NOTE: For me, the key was my giving the students lots of examples in the early part of the lesson. Children learn naturally through patterns. (Which is why a young child will call a lion a ‘cat’.)   The next lesson(s) they worked alone with the bingo chips and writing and drawing their number sentence.  HOWEVER, set up partners if you see they need a support system.  (By forming partners with someone of the same ability, the students figure things out at the same speed. Faster students will write more examples, and may move on to the next level of thinking!)

 

 

* We counted the chips at the beginning of each class and at the end. I kept them in a desk drawer.