1st Grade: Adding Doubles & Doubles Plus 1

Addition strategies help students do mental math quickly in their heads and lead to automatically with math facts. Teaching these strategies is difficult and it takes students awhile to really get it.

The first step is getting student "buy in". The already know how to add 2 + 2 by drawing circles or counting on, we need to convince them that this new "magical" strategy is super cool and going to help them do math facts in a snap!

In order for students to use doubles to add they need to recognize doubles. They have a ton of prior knowledge about doubles and that is what makes this such an effective strategy. Start by activating this knowledge with pictures and talking about things that they know come in doubles. This will give them a visual to recognize the facts, as well as give them a solid foundation of what you mean when you say "doubles". I recommend making this an anchor chart in the classroom. 

Here is an example.

Once you have introduced the concept of Doubles Eureka math has a great strategy for using your fingers to practice doubles to ten. 

Basically, you show students the doubles facts with your fingers and say the number sentence together. 

Example: Hold up your pink finger from each hand and together say, "1 + 1 = 2". Next hold up your pink and ring finger from each hand and together say, "2 + 2 = 4." Practice each fact up to 5 + 5. Here is a visual from Eureka to show you how to model with your fingers:

Here is a game students can play to practice either independently or in small group:

Doubles Aren't Trouble

Doubles Plus 1

Once students are easily recognizing and adding doubles, they can begin using this strategy to add doubles plus one. 

My favorite way of introducing this is with unifix cubes. Here is an example, make sure you use the color coding when you teach it!

Start by having students build a doubles fact with their cubes and write the addition sentence. 

5 + 5 = 10

Next, use a number line to decide who 5's neighbor is. It's 6!

Have students add 1 red cube to the top of one of their towers. 

5 + 6 = 11

Talk about the double in this problem, so they very clearly see that it is just 1 more than 5 + 5. Repeat this with lots of facts until they see the pattern. Next, start with the near doubles fact and see if they can build the hidden double. 

Example:

8 + 7 = 

Students would need to build 7 + 7. Once they all have it, they can add 1 red cube to the top of 1 tower to make 8 + 7. A huge part of doubles plus 1 is being able to visualize the hidden double. It will take them lots of practice and repetition to see it. 

Once you have done the doubles and doubles plus 1 lesson, focus on practicing doubles. Students should not practice doubles plus 1 until they quickly know their doubles. The only way it is an effective strategy is if they have automaticity with doubles!

Good luck and I look forward to hearing if any of these strategies help it "click" with the kids.