Working systematically means to solve a problem in an ordered and methodical way to ensure all outcomes are recorded.

To solve something efficiently means to solve a problem quickly whilst also maintaining accuracy.

Represent the structure of a problem with two unknowns in context

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

An efficient strategy is a when a problem can be solved:

The bar model shows two values a and b. What is the value of a?

The bar model shows two values c and d. What is the value of c?

Calculate the size of e in the bar model.

A supermarket sells 90 burgers and sausages altogether. They sell 40 more sausages than burgers. How many sausages do they sell? 

Andeep is travelling to see his relatives. The whole journey is 182 km. He travels by train for 36 km further than he does by bus. How far does he travel by train altogether? {{ }} km

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


Two rods are equivalent to the yellow.  One of them is white. What is the missing rod?

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

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

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


Two rods are equivalent to the yellow. 
One rod is four times the size of the other rod.  What rods could they be?

This lesson will soon be taken down.

Represent the structure of a problem with two unknowns in context

Lesson outcome