Adding Three Numbers by Counting Every Object Altogether

Look for this idea outside of your lessons. A cook combining three baskets of beans does the same thing. Three sources, one pot, one total. This is worth learning because real totals often come from more than two sources. Watch for it today, and when you spot it, tell someone what you noticed and how you knew.

Ask yourself where else the same idea might be hiding, then go and look. Let us look at this together. Sometimes three groups need joining. Two pinecones, three pinecones, and four pinecones sit on the porch. Push them into one pile and count them all: nine.

You can also add two at a time. Two plus three makes five, then five plus four makes nine. Both roads reach the same place. When you add three numbers, keep track of which ones you have already used so nothing is counted twice or left out. Watch out for losing track.

With three groups, it is easy to count one twice or skip one entirely. Push each group into the pile as you count it, or cross it off in your drawing. Keeping a record of what is done is how careful workers stay accurate. Say it out loud once, and then try it with real objects.