Measuring liquids and masses

Record mass in grams (g) or kilograms (kg). Record liquid volume in litres or millilitres (ml). One kg is 1000 g. One litre is 1000 ml. A liquid has both mass and volume; choose units for the attribute measured. Capacity is how much a container can hold. A volume reading tells how much liquid is inside now. Read the scale's unit and count its equal steps from zero.

To estimate mass, compare with a known mass. A small paperclip is about 1 g. A marked 1 kg weight is 1000 g. If a textbook feels close to the marked weight, an estimate near 1 kg is sensible. Check the estimate by weighing; objects of the same kind can differ.

To find the closest estimate, compare masses in matching units. 1100 g is close to 1 kg, which is 1000 g. A few grams are much farther away. To record kg and g, group each 1000 g into 1 kg: 1600 g is 1 kg 600 g.

Use matching units. Add to combine: 300 g + 100 g = 400 g. Subtract what leaves: 600 g - 100 g = 500 g. For equal groups, multiply: 2 bags of 300 g total 600 g. To find a difference, subtract the smaller amount: 800 ml - 300 ml = 500 ml. Count 500 ml portions: 500, 1000, 1500. Thus 1500 ÷ 500 = 3 portions.

One litre is 1000 ml. Convert first. Count portions to reach the total. For equal shares of liquid or mass, divide the total by the number of shares. Share 1400 ml among four: three rounds giving 100 ml each use 1200 ml. Next give 10 ml each per round: 40, 80, 120, 160, 200 ml. Five rounds add 50 ml each: 1400 ml ÷ 4 = 350 ml.

Check an estimate's unit as well as its number. 5 kg means 5000 g, not 500 g. Compare each proposed estimate with a known mass in matching units. Choose the value closer to that benchmark. Being able to hold an object does not by itself tell you its mass.