Officials said protests took place at 17 places across the state, including Ballia, Aligarh, Gautam Buddh Nagar and Varanasi.
Angry over the children's death, hundreds of people took to the streets and protested near the local police station demanding action against school teacher and officials responsible for the calamity.
At least two children of a government primary school in Bihar's Saran district died on Tuesday after consuming the mid-day meal. Also, Over 80 children have taken ill fell, an official said.