The children continued to lay the wood side by side. When it ran out, they were perplexed.
"We don't have enough to finish the bridge!"
They stood around for many minutes, stepping on their bridge, counting the pieces that were side by side, and then looking around the yard for any loose pieces of wood they might have missed.
"I know! Let's take half of the pieces and move them so that we can make the bridge longer! We'll just have to walk one at a time instead!"
The children realized that if they narrowed their bridge they could double the length by moving the pieces in different positions. The amount of wood they used hadn't changed but their problem solving allowed them to complete a workable way of crossing the water.
Success! The children children spent the majority of their outdoor time racing one by one across the big puddle. They even tried driving the tricycles across it - the process of experimentation in doing so led to some amazing conversations about the weight of the bike and if the wood would hold it, the position of the wood pieces and if they would stay in place while being driven on, and how fast the bike could be driven across without the pieces shifting and becoming ineffective.
The outdoors is full of possibilities for children to mathematize their play; this authentic experience of crossing the puddle motivated the children to engage in robust math that incorporated measurement and problem solving!