Count together: addition

Combine two collections and represent the total with addition.

An idea to revisit first: More, fewer, equal →

Think with objects in front of you

Bring both groups together and count every object once.

Place three marbles beside two. Count all the marbles together, not only the original two or the new three. There are five.

Write 2+3=5 for two plus three making five. The sign + means addition. The sign = says 2+3 and 5 name the same quantity.

Now start with three and add two. No marble has appeared or disappeared, so the total is still five. The order of the two groups does not change their total.

Writing 5=2+3 also expresses equality. The equation is a way to record the story. Say which groups were combined, not only the answer.

Listen one paragraph at a time

1/4

2/4

3/4

4/4

Now move the objects yourself

Change the two groups. Predict the total before revealing it. Swap their order and compare.

Tap objects to mark what you have counted. There is no time limit.

First collection3

Second collection3

First collection

Second collection

You may use small toys or blocks instead of the screen. Explain what stayed the same and what changed.

Check your idea with different examples

Two pencils are added to four. How many altogether?

Combine three and four, then combine four and three. How do the totals compare?

What does each number in your addition name in the story?

You may speak or draw on paper. Look for these ideas in your explanation.

I included both groups.I distinguished the starting, added and total amounts.

Continue reading, or pause here

What happens when some objects are taken away? Continue to subtraction.