Conservation of Matter
Aligned to 5-PS1 — Next Generation Science Standards.
What this lesson teaches
Matter is made of particles too small to see. When substances mix, dissolve, or change state, the total amount of matter stays the same — mass is conserved even when it looks different.
Worked examples
Example 1
Dissolve 10 g of salt in 100 g of water: the salt seems to vanish, but the solution still weighs 110 g. The matter is still there as particles.
Example 2
Burn a log and the ash weighs much less — but add the gases and soot that went up the chimney and the total is unchanged.
Example 3
Seal a fizzing tablet and water in a closed bottle and weigh it. The mass is the same before and after, because the gas cannot escape.
Practice questions
- If ice melts in a sealed bag, does its mass change? Explain.
- Where does dissolved sugar go?
- How could you prove matter is conserved when a tablet fizzes in water?
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
Conservación de la Materia
La materia está formada por partículas demasiado pequeñas para verse. Cuando las sustancias se mezclan, se disuelven o cambian de estado, la cantidad total de materia permanece igual — la masa se conserva aunque tenga una apariencia diferente.
Ejemplo 1: Disuelve 10 g de sal en 100 g de agua: la sal parece desaparecer, pero la solución sigue pesando 110 g. La materia sigue ahí en forma de partículas.
Ejemplo 2: Quema un tronco y la ceniza pesa mucho menos — pero suma los gases y el hollín que subieron por la chimenea y el total no cambió.
Ejemplo 3: Sella una tableta efervescente y agua en una botella cerrada y pésala. La masa es la misma antes y después, porque el gas no puede escapar.
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