Positive and Negative Numbers
Aligned to 6.NS.C.5 — Common Core State Standards for Mathematics.
What this lesson teaches
Negative numbers describe amounts in the opposite direction from positive ones, with zero as the starting point. They model real things like temperatures below freezing, elevation below sea level, or money owed.
Worked examples
Example 1
A submarine 40 feet below sea level is at −40 ft. If it rises 15 feet, it moves toward zero: −40 + 15 = −25 ft, still below the surface.
Example 2
A bank account at −$35 gets a $50 deposit: −35 + 50 = $15. The account crossed zero into the positive.
Example 3
−7 and 7 are opposites: same distance from zero, opposite directions. Their sum is 0.
Practice questions
- Write a signed number for 'a debt of $20'.
- The temperature is −3°C and drops 5 more degrees. What is the new temperature?
- Order these from lowest to highest: 2, −7, 0, −1, 5.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Números Positivos y Negativos
Los números negativos describen cantidades en la dirección opuesta a los positivos, con el cero como punto de partida. Representan cosas reales como temperaturas bajo cero, elevación bajo el nivel del mar o dinero que se debe.
Ejemplo 1: Un submarino a 40 pies bajo el nivel del mar está en −40 pies. Si sube 15 pies, se acerca al cero: −40 + 15 = −25 pies, aún bajo la superficie.
Ejemplo 2: Una cuenta bancaria en −$35 recibe un depósito de $50: −35 + 50 = $15. La cuenta cruzó el cero hacia lo positivo.
Ejemplo 3: −7 y 7 son opuestos: la misma distancia del cero, en direcciones contrarias. Su suma es 0.
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