Time, liquid volume, and mass problems (grade 3) · lesson

How long did it last?

💡 To find how long something lasts, count up from the start time to the end time.

Count whole hours first. Each hour is 60 minutes.

Then count the extra minutes. It helps to jump to the next o'clock first.

🧠 Let's work it out

A show runs from 3:10 to 4:25. How many minutes long is it?

What do you think comes next?

💡 Add the minutes to the start time, and move to the next hour when you pass 60.

If the minutes stay under 60, just add them. 2:05 plus 30 minutes is 2:35.

If you pass the hour, jump to the next o'clock first. Then add the minutes that are left.

🧠 Let's work it out

Start at 8:50. Add 25 minutes. When does it end?

What do you think comes next?

💡 Liters measure how much liquid a container holds, and you add, subtract, or share them like any number.

A liter is about as much as a big water bottle holds.

Pour two amounts together: add. Pour some out: subtract. Pour equal amounts into jugs: divide.

🧠 Let's work it out

A tub holds 16 liters. It is poured equally into 2 buckets. How much goes in each?

What do you think comes next?

💡 Kilograms measure how heavy something is, and you add or subtract them to compare or combine.

Mass is how heavy a thing is. A big book has a mass of about 1 kilogram.

To find a total mass, add. To find how much heavier one thing is, subtract.

🧠 Let's work it out

3 bags have a mass of 5 kg each. A box has a mass of 2 kg. What is the total mass?

What do you think comes next?