Every measurement in science starts with one of these seven.
REMEMBER: Scientists everywhere use the same 7 base units so their measurements always match. Each base unit measures one quantity: length, mass, time, temperature, amount of substance, electric current, or light intensity. Every other unit is built from these seven.
Part 1 — Meet the Seven
Click each tab. For every unit, learn three things: what it measures, its symbol, and a real-world anchor you can picture.
Part 2 — Match Quantity to Unit
Click a quantity on the left, then click its base unit on the right. Matched pairs lock in green. Try for a perfect 7-for-7!
QUANTITY (what you measure)
BASE UNIT (symbol)
Pick a quantity to begin.
Tries: 0
Part 3 — Base Unit Challenge
Ten questions. Watch out for the everyday units that are NOT base units — they are the traps!
Question 1 of 10
Score: 0
WORD BOX
quantity
something you can measure, like length, mass, or time
base unit
one of the 7 official SI units that all other units are built from
derived unit
a unit built by combining base units (like liters for volume or m/s for speed)
mass
the amount of matter in an object — the same everywhere, even on the Moon
weight
the pull of gravity on an object — changes from place to place (not the same as mass!)
mole (mol)
the chemist's counting unit: 6.022 × 10²³ particles
kelvin (K)
the science unit for temperature; 0 K is the coldest anything can ever be