The difference is the result of subtracting one number from another. How much one number differs from another.

Compare the structure of problems with one or two unknowns

Maths

In this unit pupils will compare and represent the structure of problems with two unknowns using a bar model. They will systematically solve problems with two unknowns using trial and improvement. In the future unit this understanding is formalised through the use of algebraic notation. 

In the prior unit pupils explained how to balance equations with addition or subtraction expressions and used knowledge of balancing equations to solve problems. In this unit pupils will compare and represent the structure of problems with two unknowns using a bar model. They will systematically solve problems with two unknowns using trial and improvement.

Solving problems with two unknowns

Two rods are equivalent to the dark green rod.  One of them is red. What is the missing rod?

Two rods are equivalent to the dark green rod.  One of them is light green. What is the missing rod?

Two rods are equivalent to the yellow rod.  What could be the missing rods be?

Two rods are equivalent to the pink rod.  What could be the missing rods be?

Two rods are equivalent to the blue rod.  There is a difference of red between the rods.  What rods could they be?

Two rods are equivalent to the dark green. One rod is twice the size of the other rod. What rods could they be?

Write in the missing number: 30 + {{ }} = 180

Tick the possible solutions for ___ + ___ = 180

Without applying commutativity, how many possible solutions are there if each of the missing values are integers? ___ + ___ = 10  

Which pair of numbers that sum to 10 have a difference of 4? ___ + ___ = 10        

Write the number that is two-thirds the size of 15

This lesson will be removed by end of Summer Term 2025.

Compare the structure of problems with one or two unknowns

Lesson outcome

This lesson will be removed by end of Summer Term 2025.