# Lesson 1

Unidades estándar de medida

### Lesson Purpose

### Lesson Narrative

In grade 1, students learned how to measure length by laying multiple copies of a shorter object end to end without gaps or overlaps. In this lesson, students use these measuring skills to measure the length of objects by iterating with straws and centimeter cubes. In the first activity, students use different length units when measuring the same objects and see that this leads to different measurements. In the second activity, all students use the same length unit (centimeter cubes) and see they all find the same measurement. In the lesson synthesis, students are introduced to the **centimeter **as the length of a centimeter cube. Students will use the centimeter as a length unit in future lessons.

Give students access to centimeter cubes during the cool-down.

- Representation

### Learning Goals

Teacher Facing

- Measure by iterating same-size length units.

### Student Facing

- Midamos longitud.

### Required Materials

Materials to Gather

### Required Preparation

Activity 1:

- Create a 40-cm length of string or ribbon for each group of 2–3.
- Create five 10-cm length straws for half of the groups of 2–3.
- Create ten 5-cm length straws for half of the groups of 2–3.

Activity 2:

- Gather a connecting cube to display in the activity synthesis. Students will not need connecting cubes for this activity.

### 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)
- Five in a Row: Addition and Subtraction (1–2), Stage 6: Add within 100 with Composing (Supporting)