What's a Treebot? is the ninth mission in WorldBuilder.
Pick up the plans for the Treebot and build it with the nearby stacks of blue and green bricks, as well as the energy brick. Clear the way for the Dirtbuggy to reach the goal by uprooting and planting trees as you see fit. Then simply drive the Dirtbuggy to the goal.
Use the Dirtbuggy to pick up the plans for the Tugboat. Move the Treebot near the river and the fresh Energy Brick, take it apart, then use the parts to build a Tugboat on the water. Then take apart the Buggy near the water, and use the Tugboat to ferry the parts to the bonus goal. Simply build a Buggy on the bonus goal afterwards.