Seven year olds.
The children looked at photos and observed the details on a turtles surface. They drew several turtles using black crayons on a large piece of paper. They chose their best work, focusing on details and shape. They used a black pen to draw their turtles and painted them with water colours and fine brushes. They chose a background colour that enhanced their work. I was impressed at how decisive they were at this point. They glued their work on the chosen background.
They had an opportunity to repeat the exercise using strong dye and cotton buds to apply the colour.