NAIROBI, Kenya, Nov. 29 — The British teacher in Sudan who let her 7-year-old pupils name a class teddy bear Muhammad was found guilty on Thursday of insulting Islam and sentenced to 15 days in jail and deportation. Under Sudanese law, the teacher, Gillian Gibbons, could have spent six months in jail and been lashed 40 times. “She got a very light punishment,” said Rabie A. Atti, a government spokesman. “Actually, it’s not much of a punishment at all. It should be considered a warning that such acts should not be repeated.” British officials, meanwhile, were furious. As soon as the news broke that Ms. Gibbons had been convicted, the Foreign Office in London, which had called the whole ordeal “an innocent mistake,” summoned the Sudanese ambassador — for the second time in two days. “We are extremely disappointed,” said Omar Daair, spokesman for the British Embassy in Khartoum, the capital. Ms. Gibbons, 54, has been in jail since Sunday, and Mr. Daair said her sentence would i