# Lesson 12

Problemas-historia y diagramas

### Lesson Purpose

### Lesson Narrative

In previous lessons, students solved different story problems within 50 and compared different diagrams and methods. Students interpreted and used tape diagrams to represent Compare story problems.

The problems in this lesson include some of the more challenging types (for example, Add To, Start Unknown). Students are introduced to tape diagrams as a way to represent the known and unknown quantities in Add To and Put Together / Take Apart problem types. Students are encouraged to find the unknown values in the way that makes the most sense to them. Students have opportunities to practice composing and decomposing a ten when using strategies based on adding or subtracting by place.

- Engagement

Activity 1: Interpretemos el diagrama

### Learning Goals

Teacher Facing

- Make sense of diagrams that represent story problems.
- Solve one-step story problems within 100.

### Student Facing

- Demos sentido a los diagramas y resolvamos problemas-historia.

### Required Materials

Materials to Gather

Materials to Copy

- Card Sort Story Problem and Diagram Cards, Spanish

### Required Preparation

Activity 2:

- Create a set of cards from the blackline master for each group of 2.
- The sets of cards will be used again in the next lesson.

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 15 min |

Activity 2 | 20 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

### Suggested Centers

- Target Numbers (1–5), Stage 5: Subtract Two-digit Numbers (Addressing)
- Capture Squares (1–3), Stage 4: Subtract within 20 (Addressing)
- Shake and Spill (K–2), Stage 5: Cover (up to 20) (Supporting)

### Print Formatted Materials

Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.

Student Task Statements | docx | |

Lesson Cover Page | docx | |

Cool Down | Log In | |

Teacher Guide | Log In | |

Teacher Presentation Materials | docx | |

Blackline Masters | zip |