The mass of an object is how heavy the object is.
The basic unit of mass is the gram. A gram is one thousandth of a kilogram.
1,000 grams = 1 kilogram
eg a pen has a mass of about 6 grams (g).
The main units of measurement for mass at school is grams (g), kilograms (kg) or tonnes (t).
eg An adult has a mass of 85kg
eg An iphone 15 has a mass of 220g
eg A Boeing 747 jumbo jet has a mass of 400t
The weight of an object is a combination of the mass plus the force of gravity.
Weight is measured in Newtons (N).
eg An adult has a mass of 85kg. On Earth, they weigh about 850N but on the moon they would weigh about 1/6 of this, about 142N, because the gravity on the moon is about 1/6 of Earth's gravity. The mass of the adult remains at 85kg on the Earth and the Moon.