Understanding what kilo- (x1000), centi- (÷100), and milli- (÷1000) mean and how they modify base units.
Where your child meets this in real life: Understanding why a kilometre is longer than a metre, or why milligrams are tiny doses in medicine
SEAGReady breaks understand metric prefixes into 3 steps, taught in order so each skill builds on the last.
Understand that kilo- means 1000 times a base unit and how it applies to metre, gram, and litre
Understand that centi- means 1/100 of a base unit and how it creates smaller versions of units
Understand that milli- means 1/1000 of a base unit and distinguish it from centi-
Three free sample questions from our understand metric prefixes course. Every question comes with a full explanation, and hints that guide without giving the answer away.
Sean is cycling a 3 kilometre route around Strangford Lough. How many metres is this?
Answer: A. 3000 metres
Kilo- always means 1000 times the base unit. 1 kilometre = 1000 metres So 3 kilometres = 3 x 1000 = 3000 metres
Stuck? Start here: What does the prefix kilo- mean?
How many centimetres are in 1 metre?
Answer: B. 100 centimetres
Centi- means one hundredth (1/100) of the base unit. A centimetre is 1/100 of a metre. So 100 centimetres make 1 metre. 1 m = 100 cm
Stuck? Start here: What does the prefix centi- mean?
How many millimetres are in 1 centimetre?
Answer: C. 10 millimetres
Centi- means 1/100 of a metre, so 1 m = 100 cm. Milli- means 1/1000 of a metre, so 1 m = 1000 mm. To find mm in 1 cm: 1000 divided by 100 = 10 So 1 cm = 10 mm
Stuck? Start here: Centi- means 1/100 and milli- means 1/1000
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Conor is training for a charity run. The route is 5 kilometres long.
How many metres is the route?
5 km = ? m
Step 1 of 3
Conor is training for a charity run. The route is 5 kilometres long.
How many metres is the route?
The route is 5000 metres long.
The key insight: Kilo- always means 1000 - whether it's kilometres, kilograms, or kilolitres!
Watch out: 5 km = 500 m. Kilo means ×1000, not ×100. There are 1000 metres in every kilometre.
These are the misconceptions we see most often in understand metric prefixes, including the ones our practice questions are specifically designed to catch.
Struggling with understand metric prefixes? The real gap is often in one of these earlier topics.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.