Get white or cream colored long stem roses (carnations work too). Cut the stem according to the picture. Get 4 glasses of food color dyed water and put one piece of stem in each color. Allow the flower to soak up the different colors.
This activity can help children with angles. Instead of measuring angles on paper, this can illustrate angles into a read life demonstration. This is active learning because as children close the door the angle changes and they can now measure it.