Hey Fiona,
I love the idea of using pictures books as a stimuli for science lessons as this is a great way of integrating oral language into the lesson.
Your science investigation is very similar to the one I shared just with a different problem to introduce the lesson. I love the idea of leaving the teddy outside as this is much more visual then just giving the children an oral problem. I can just imagine how concerned/worried the children would be about the teddy bear therefore would be very eager/engaged to help the teddy.