Addition and subtraction word problems
Solve word problems involving lengths within 100, using addition and subtraction with drawings and equations
What a learner can do afterwards
- Solve 'The rope is 45 cm long. I cut off 18 cm. How long is it now?'
- Draw a diagram (e.g. a ruler drawing) to represent a length word problem
- Write an equation with a symbol for the unknown to represent the problem
The lesson
Word problems about length ask you to find a missing length. Some problems make a length longer, so you add. Others make a length shorter, so you subtract. Read the problem carefully to decide which one it is.
A ribbon is 62 cm long. Mia glues on another piece that is 15 cm long. The ribbon gets longer, so you add: 62 + 15 = 77. The ribbon is now 77 cm long.
Before you solve, draw a quick number line or picture of the length. It helps you see whether the length grows or shrinks, so you pick add or subtract correctly.
Decide if the length grows or shrinks, write an equation with a symbol for the missing number, then solve it.
Watch it
Where it sits
This opens up
Where this leads
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.