'you would be dreaming , ' the bfg said , 'that the morning after you is saving the teacher from the river , you is arriving at school and you is seeing all the five hundred pupils sitting in the assembly hall , and all the teachers as well , and the head teacher is then standing up and saying , `` i is wanting the whole school to give three cheers for sophie because she is so brave and is saving the life of our fine arithmatic teacher , mr figgins , who was unfortunately pushed off the bridge into the river by our gym-teacher , miss amelia upscotch .