Whales class have been using their engineering minds recently within Welly Day as they have been learning how to create enormous marble runs.  The class watched videos, including Rube Goldberg machines, for inspiration.  Today they were focusing on how to speed up balls and how to slow them down.  They know that friction is an important factor and some chose to add grass to their runs.  Investigations with different balls enabled them to realise that the weight of the ball was also crucial.