Minds On

Tools to help us add

Addition is when we add two numbers together. The answer we get is called the sum. For example, 5 + 5 = 10. The sum is 10.

We can use tools like counters, a number line, or mental math to help us!

Three different kinds of counters, including circle counters, connecting blocks, and base-ten blocks.

Let's explore a number line together!

If you would like, access this Number Line with Numbers from 1 to 20 in your notebook or using the following fillable and printable document.

Number line with numbers from 1 to 20

Press the Activity button to access Number Line with Numbers from 1 to 20.

Activity (Open PDF in a new tab)

Or you can use mental math.

A person thinking about the sum of five plus five.

Let's use counters to write an addition sentence! (If you don't have counters you can use toys or other materials that you may already have. For example, Legos are a great substitute for counters!)

Pretend you are playing hockey with your friend and they have asked you to keep score. In the first game they scored 6 points. In the second game they scored 5 points. How many points did they score all together?

  • How many goals did your friend score in the first game?

Count out that many counters.

  • How many goals did your friend score in the second game?

Place that many counters right next to the first set of counters.

  • How many counters do we have all together now?
  • Create an addition sentence for the number of goals your friend scored all together. You can use a method of your choice.

Action

Activity – What is the total?

Let's practice addition in a game. You can use a spinner, roll two dice or choose a card from a deck of playing cards. You can also use a random number generator on a computer, if you prefer.

  • Use your item to choose your first number and record that
  • Use your item again to choose your second number and record that
  • Estimate what you feel the answer will be
  • Write an addition sentence and then add the two numbers together

Be sure to complete this at least 5 times!

Discussion:

What strategies did you use to estimate? Which strategies from Minds On did you use to help you solve each addition question you created?

Consolidation

Try a sudoku style puzzle

Have you ever tried a Sudoku? It's a puzzle where you need to find the missing number for the empty boxes. Each addition sentence needs to add to 20. For example, the first row has 9 counters in the first box and 7 dots in the third box. What number should be in the second box? 9 + (Blank) + 7 = 20.

Be sure to record an addition sentence for each!

Sudoku with 3 to 4 boxes for each row. Two of the boxes need to be filled in with different numbers

Reflection

How do you feel about what you have learned in this activity?  Which of the next four sentences best matches how you are feeling about your learning? Press the button that is beside this sentence.

I feel...

Now, record your ideas about your feelings using a voice recorder, speech-to-text, or writing tool.

Press ‘Discover More’ to extend your skills.

Mental math

One of the ways we can add is through estimation. Estimating can help us when we are adding and we want to find an approximate number to our question.

An example of a mental math strategy is simplying the numbers we are trying to add. Let's take the numbers 28 and 12 and make them easier to add.

28 + 12 = (Blank)

The number 28 is close to the number 30, so we will change it to 30. The number 12 is close to the number 10, so we will change it to 10. It is easier to add 30 and 10.

= 30 + 10 = (Blank)

= 40

Give it a try! Find the answer to 21 plus 18.

  • We can simplify the numbers to help us estimate.
  • What would we do with number 18?
  • What would we do with number 21?
  • Now that we simplified the numbers it is easier for us to add them together. We can even add it together using mental math.
  • What would the numbers added together be?
  • How can we check our work?