Students will be able to add one more or 10 more using pictures to represent quantities.
- Write the following problem on the board: "Sara collects seashells. She has 10 seashells in her collection already. Then, she goes to the beach and finds 4 more seashells. How many seashells are in her collection now?"
- Think aloud about the problem. Remind students that she started with 10, and then found more shells, so students should add to find the total number.
- Allow students think time, and then choose a few students to share a solution. Ask students how they solved the problem. For example, did students count on from 10 using the number line, or have the fact memorized?
Explicit Instruction/Teacher modeling(5 minutes)
- Tell students that today they will practice using drawings to solve addition problems.
- Remind students that when you add, you are solving for the total number. Today, students will be focusing on adding one and 10 to a number. One and 10 are sometimes called "friendly numbers" because there are patterns that can help students add using these numbers.
- Return to the seashell problem. Tell students that you do not have seashells, so you are going to solve the problem with unifix cubes.
- Think aloud, "I know Sara started with 10 seashells." Count out 10 individual unifix cubes and display on document camera or on the rug with students sitting in a circle. "Then she found four more." Add four more cubes.
- Ask students for suggestions of ways to organize the cubes to make it easier to solve the problem.
- Guide students in understanding that since 10 is a friendly number, it would be helpful to create a group of ten and then count on, rather than counting starting at one.
- Join 10 unifix cubes together and model counting, "10, 11, 12, 13, 14. Yes, she has 14 seashells total."
Guided Practice(10 minutes)
- Explain to the students that blocks are not always available to use when adding, and today you will teach them how to draw a picture that will help them add.
- Hold up the unifix cubes joined together to create a ten. Say, "Rather than draw each individual cube I will draw a long rectangle to show 10." Draw a long rectangle to represent a base-ten rod.
- Say, "Now I will draw four small squares to show the additional seashells." Count aloud as you draw four squares.
- Write the equation 10 + 4 = 14 under the sketch of the base-ten blocks.
- Guide students to solve addition problems that include adding one more and 10 more. Read the problem aloud, sketch base-ten blocks, and then write the equation below the sketch.
- Include problems such as 7 + 10. Remind students of the steps to sketch the base-ten blocks. Model starting at 10 and counting on, or thinking about how you know that 17 is 10 more than seven.
Independent working time(10 minutes)
- Distribute individual whiteboards and dry erase markers, or paper folded into fourths, to students.
- Give students addition problems to practice solving for one or 10 more, for example 6 + 10 or 8 + 1. Say the problem aloud, and guide students to represent the problem with a sketch of base-ten blocks..
- Instruct students to write an equation below the sketch to solve the problem.
- Have students work to build the parts of the addition problem with unifix cubes before sketching the cubes to represent the problem.
- Work with students to solidify understanding of "one more" before introducing "10 more."
- Provide flash cards to students with addition facts to 20. Although students may have facts memorized, challenge them to explain their thinking using sketches of base 10 blocks.
- Instruct students to compose a 10 when adding two numbers with teen totals, for example nine and six. Guide them in understanding that 9 + 6 = 10 + 5.
- Formatively assess student understanding of using pictures to represent addition as they work on individual whiteboards or papers to solve problems.
- Ask students to share how drawing the problem can help them to solve the problem.
Review and closing(5 minutes)
- Call students back to the rug and ask them to give you a thumbs-up if sketching the problem helped them to solve it more easily.
- Review different strategies for solving addition problems, including counting on on a number line or counting objects. Remind students that today they learned a new strategy of sketching a 10, rather than drawing 10 individual squares, that can help them solve for 10 more.