Grams and litres: convert like quantities
Connect g with kg and mL with L, without confusing mass with volume.
Begin with the activity ↓Is one litre always one kilogram?
Grams and kilograms measure mass; millilitres and litres measure volume. Their factors of 1000 do not make mass and volume interchangeable.
One grain bag is labelled 1.5 kg and another 500 g. Match their units to compare them. Since 1 kg=1000 g, the first bag is 1500 g.
Read g as gram and kg as kilogram. They measure mass, often casually called weight. A physically larger object need not have more grams of mass.
Juice volume can be written in millilitres, mL, or litres, L. Since 1 L=1000 mL, 750 mL is 0.75 L. No juice was added: the same volume has a new label.
Do not directly convert kilograms to litres. Equal-volume containers filled with different materials can have different masses. Relating volume to mass needs information about the material and its properties.
Adding 2 L and 250 mL gives 2250 mL, or 2.25 L, not 252 L. Use the same matching-unit approach within grams and kilograms.
Also distinguish current contents from capacity. A 1 L container holding 0.4 L has room for 0.6 L more. The capacity of that same container is the reference.
Listen one paragraph at a time
Hold on to this distinction
g↔kg and mL↔L each stay within one quantity type. kg↔L is not a simple unit conversion. Name the quantity before converting.
Change it and check
Choose mass or volume, then switch between larger and smaller units of that type. Changing types starts a new example.
1.2 kg = 1200 g
1 kg = 1000 g
Check the same quantity in a reference unit: 1200 g
The quantity is unchanged. Units of a different quantity type cannot be converted directly.
No kg-to-L conversion is made without material information. You can use labels without weighing substances or filling containers.
Try with paper and objects
Find mL and L markings on empty containers and rewrite them consistently. Put g and kg food labels in a separate table; do not mix the two quantities.
Check and explain another example
Check your idea 1
Check your idea 2
Apply it in a new setting
Connect the answer to its unit
Return to the explanationCompare with a solution
2.075 · L
Since 75 mL=0.075 L, the sum is 2.075 L.
Does your explanation include these ideas?
Explain aloud or in a drawing, then check your ideas. Different wording can express the same meaning.
Continue, or pause here
Read the minute intervals and the continuous movement of the hour hand.