The old wooden shed

I was walking home from a tiring,long day at school and then I realised there were annoying road works,so I had to take the long way around.I went round the corner,up the side street and down the path.I noticed that along the rows of cottages there was an old wooden shed with shaky glass windows,I was about to walk on but when I turned my head I thought I saw something move inside,

I knocked on the window,it shook a bit but nothing moved,I knocked again,still nothing moved,I went inside...