Problem
Jason makes a train from a green rod, a yellow rod and a black rod.  Kim makes her train from a green rod, a black rod and a blue rod?  Who has the longest train?

What is this problem about?
This is an opportunity for the children to compare lengths. It can be done by calculation if children know the "value" of the cuisenaire rods or by using the rods and comparing the lengths.

Achievement Objectives
Measurement (Level 1)
- order and compare lengths using measuring language.

Mathematical Processes
- devise and use problem solving strategies to explore situations mathematically;
- use equipment appropriately.

Resources
- cuisenaire rods
- Blackline master of the problem

Specific learning outcomes
The children will be able to:
- compare two lengths (either directly or by calculation)

Teaching Sequence

1. Begin the lesson by forming trains with cuisenaire rods.  Show a train using 2 rods and ask the children to make a larger one. If the children have used the number values for the rods ask them to explain their working.
2. Pose the problem.
3. Brainstorm for ways to solve the problem (use equipment, addition).
4. Let the children work on the problem in groups of 2-3. As they work ask questions that focus their thinking on measurement:
   Which is the longest train?
   How did you find that it?
   Can you think of another way that you could have found out which train was longer?
5. Share solutions.

Extension to the problem
Find a train that is longer than Jason's but shorter than Kim's.

Solution
Kim's is longer (19 compared to 15, or a crimson rod longer)