Addition with Triangle Flash Cards

Est. Class Sessions: 1

Developing the Lesson

Introduce Triangle Flash Cards. Display the Large Triangle Flash Card Master. Place three buttons on the corner with the circle. Place one button on the corner with the square. Slide the three-button pile to the third corner that is shaded. Record a 3 in the corner with the circle to indicate where the three buttons were originally placed. Repeat this process with the one button. Emphasize that the new pile shows the total number, the sum, of the buttons. Replace the four buttons with the number 4. Ask students to record a number sentence to show the action that took place. See Figure 1.

Find Fact Families on Triangle Flash Cards. Next place 1 button on the corner with the square and write the number 4 in the corner with the shaded triangle.

Ask:

I have four buttons. One button is [red]. How many buttons are not [red]? (3)
Where does the three go on the triangle flash card? (on the corner with the circle)
What number sentences represent this story?
(4 = 1 + 3; 4 = 3 + 1; 4 − 1 = 3)
Show how 4 − 1 = 3 matches the story. (I have 4 buttons and take the one red button away leaving 3 buttons.)
Show how 3 + 1 = 4 matches the story. (I need to find the number plus 1 that gives you 4.)

Next place 1 button on the corner with the circle and write the number 4 in the corner with the shaded triangle.

Ask:

I have four buttons on my coat. One fell off my coat. How many buttons are left on my coat? (3)
Where does the three go on the triangle flash card? (on the corner with the square)
What number sentences represent this story?
(1 + 3 = 4; 4 − 1 = 3; 3 + 1 = 4)
Show how 4 − 1 = 3 matches the story. (I started with 4 buttons and one fell off.)
Show how 1 + 3 = 4 matches the story. (I need to find the number of buttons plus 1 button that equal 4 buttons on the coat.)
Do these sound familiar? (Yes. They are the same number sentences that were recorded for the earlier problem.)
Do the triangle flash cards match? (No, but they are close. The addends are in the square and circle. The order of these does not matter.)
Write a story for 4 − 3 = 1. (Possible response: There are four buttons on the coat. One is buttoned. How many are unbuttoned?)
Does anyone remember what all these facts together are called? (a fact family)

Write all the number sentences for the fact families that relate 4, 1, 3 on the board.

Then ask:

Is 3 − 4 = 1 a number sentence in this fact family? (No. 3 – 4 is not 1. If I take 3 away from 4 the answer is less than 0 or –1.)

Number Sentences and Stories. A take-away story seems to warrant a subtraction number sentence just as a join story seems to warrant an addition number sentence. A student may write an addition number sentence with a missing addend for a take-away story if they think of the solution as a problem with a missing addend. The operation is the action taken to solve the problem and may not match the actual situation in the problem.

Display the Large Triangle Flash Card Master again. Repeat the discussion above with different sets of addends. (e.g., 2 and 3, 1 and 4, and 0 and 2). Ask students to write the number sentences for addition and subtraction situations represented on the Triangle Flash Card and tell a story that matches the number sentence.

Have students review fact families using the Fact Families with Addition Triangles pages in the Student Activity Book. These pages use some of the facts from Groups A and B. Begin by eliciting from the class what should be filled in for the numbers that are missing in the various positions in the triangles on the page.

Connect Stories to Number Sentence.

When students have finished, discuss the pages aloud and ask prompts similar to the following for a few more fact families:

Who can tell us an addition story using the numbers in Question A? (Possible response: I had 2 pennies in my pocket. I found one on the ground. Now I have 3 pennies.)
Write a number sentence for your story. (Possible response: 2 + 1 = 3)
How can we change that story to make it a subtraction sentence? (Possible response: I had 3 pennies in my pocket. I lost one. Now I have 2 pennies.)

Use the Fact Families with Addition Triangles pages in the Student Activity Book with the Feedback Box to assess students' abilities to represent addition and subtraction situations using number sentences and stories [E1], demonstrate fluency with the addition facts in Groups A and B [E7], and determine the unknown number in an addition or subtraction sentence relating three whole numbers for the facts in Groups A and B [E8].

Ask students to explain why there are only two number sentences in the fact family for the numbers shown on the triangle flash card in Question B. Students should notice that since the two addends are the same, there are only two number sentences that can show the relationships between the numbers.

Ask students to share the stories they wrote in Questions I and J.

Ask:

What number sentence matches your story?
Think about the situations. Which one did you write as addition sentences? (join, part-whole)
Which one did you write as subtraction sentences? (take away, compare)

Ask students to share their responses to Questions K and L. In these questions, the fact families are listed incorrectly. This is a common error among students. Remind students to connect the number sentences to stories to make sense of them.

Check Fluency with Addition Facts. Distribute and ask students to cut apart the cards on the Triangle Flash Cards: Group A and the Triangle Flash Cards: Group B pages you copied from the Teacher Guide. Also ask students to remove the Sorting Board and Addition Facts I Know page from their Student Activity Book. Ask them to compare their flash cards to the flash card on the display. Tell students that they will focus on practicing the addition facts in Groups A and B. Tell students to find a partner. Then describe the steps they should use to practice their facts with the Triangle Flash Cards. These directions are also on the Triangle Flash Cards: Note Home Homework Masters.

One partner chooses a flash card and covers the largest number (in the shaded corner).
The other partner adds the numbers in the other corners.
Using the Sorting Board page in the Student Activity Book, students work through the cards dividing them into three piles: Facts I Know Quickly, Facts I Can Figure Out, and Facts I Need to Learn.
The student displaying the flash cards helps his or her partner find the facts from the first pile, Facts I Know Quickly, on his or her Addition Facts I Know chart so the student who is adding can circle the known facts easily. The cards from the first pile can now be clipped together and placed in an envelope for storage. They then practice again using cards from the last two piles.
Partners switch roles and repeat the procedure. Make it clear to students that for each round, only the student adding records facts from the first pile.

Students use the Triangle Flash Cards: Groups A–B, the Sorting Board, and the Addition Facts I Know chart to assess their fluency with the addition facts in Groups A–B [E7].

Ask students to store their Sorting Board and Addition Facts I Know charts from the Student Activity Book in a safe and central place in the classroom. As students progress through each unit, students will be asked to assess and track their progress. The Triangle Flash Cards: Note Home Homework Masters should be copied to provide a set of directions and tools for use at home.