There was plenty of room on the playground at El Monte Elementary School on Monday.
"We had 163 students absent out of 468 students," said School Superintendent Dick Nicoll.
The reason is parents are concerned about a possible outbreak of the H1N1 virus.
Fourth grader Brian Matamet spent the day with his family at the park.
"Because we heard about the kids at El Monte School who were sick," said Matamet.
The worry comes four days after Contra Costa health officials announced the death of a 9-year-old El Monte student who had the H1N1 virus. Karen Perez also had a secondary bacterial infection.
Then on Saturday, because of a computer glitch, school officials sent out a series of confusing telephone messages. The first was meant for teachers. It named two additional students with flu-like symptoms and gave instructions for teachers wishing to stay home.
Later, there was a second message intended for parents, but with much less information. Then, there was a third call.
"What made it worse was that third call that said, 'disregard that one from the principal, it wasn't meant for you.' So, I think that made people kind of wonder, what do you mean it wasn't meant for us?" said parent Kristine Berkson.
Many parents sent their kids to school -- with an extra lesson in hygeine.
"My kids are trained. They're clean in my house. They're clean everywhere," said parent Claudio Castro.
"I mean, what are you going to do? Keep them locked up?" said parent Lyle Wiens.
According to the superintendent, the two El Monte students with flu-like symptoms are improving. But they will not be back to class for the remaining two days of the school year.