The purpose of this Warm-up is to elicit what students know about length measurement and about units of measurement. While no unit is specified for the ruler in the image, students are likely to bring up centimeters (given the way each 1 unit is partitioned into 10 smaller parts, as seen on centimeter rulers). The work here prepares students to think about the relationship between meters and centimeters later in the lesson.

• Consider sharing that the large insect is a stick insect. (The longest species of stick insect ever found measured more than 60 cm.) The small insect is a green potato bug.
• “Si cada unidad de la regla mide 1 centímetro, ¿aproximadamente cuánto mide la chinche de papa?” //  “If each unit in the ruler is 1 centimeter, about how long is the potato bug?” (1 cm) “¿Y el insecto palo?” // “What about the stick insect?” (About 16 cm with the antennae, about 12 cm otherwise.)

• “¿Cómo organizaste las partes de 1 centímetro? ¿Cómo las contaste?” // “How did you organize and count the centimeter pieces?”
• “¿Cómo puedes asegurarte de que hay 100 partes de 1 centímetro?” // “How can you make sure there are 100 centimeter pieces?”

• “¿Cómo decidiste si las medidas en centímetros de Priya eran correctas o no?” // "How did you decide whether Priya's measurements in centimeters were correct or not?"
• “¿Cómo puedes usar las tiras que hicimos para explicar tu decisión?” // "How could you use the strips we made to explain why this happens?"