The purpose of this Number Talk is to elicit strategies and understandings students have for adding a one-digit number to a two-digit number. These understandings help students develop fluency and will be helpful later in this lesson when students need to be able to add within 50.

• “Al encontrar el valor de una suma con números grandes, ¿cómo les ayuda buscar distintas maneras de formar 10?” // “How does looking for ways to make 10 help to find the value of the sum with larger numbers?” (You can make a ten with the ones and then add the other tens back on. , , .)

The purpose of this activity is for students to learn Stage 3 of the How Close? center which was introduced in grade 1. In this stage, each student picks 7 cards and chooses 4 of them to create 2 two-digit numbers. Each student adds the numbers and writes an equation. The student whose sum is closest to 100 wins a point for the round. It is recommended that at this point in the year, students begin with a target number of 50 instead of 100.

If students are not yet able to make 2 numbers that get close to 50, encourage them to choose 2 cards, make a two-digit number, and represent the number with connecting cubes. Students determine how many more cubes they need to get to 50. Then students choose the 2 cards that will have a value closest to that number.

In this activity, students find the value of sums with larger numbers using any method that makes sense to them. They may represent their thinking using connecting cubes, drawings, equations, or words. Monitor for the ways students use methods based on place value, including the language they use to describe composing a ten when adding tens to tens and ones to ones (MP3, MP6).