I got the recipe for blueberry colored play-dough from mini-eco. As in our last experiment with turmeric, I multiplied it out for mass classroom-quantity.
The room smelled delicious as the blueberries reduced. The children predicted what color the the dye would make the dough: blue, purple, and red.
All the adults came by and smelled it expecting a sweet smell (I kept thinking grape bubble gum), but alas it just smelled like plain dough. To tie it all together we read Blueberries for Sal (they were totally engrossed in the story) and practiced wringing the letter B.