When parents shuffle their children off to school in the morning, the bedrock assumption is that their kids will be safe. But in Contra Costa County last week, that notion was again challenged; once again, the culprit seems to be incompetent administration.

For more than a year now, this newspaper and these editorial pages have detailed how various Contra Costa school districts have failed to properly follow mandatory state reporting laws on child abuse. The districts have either failed to properly train employees about those relatively simple laws, have incompetently applied them -- or both.

The result is school settings that belie the parental expectation of safety. In a number of cases, the child abuse that this incompetence tolerated -- either directly or indirectly -- has caused the districts involved to spend millions of taxpayer dollars to settle legitimate lawsuits.

Now a different but related display of incompetence has reared its head.

A 32-year-old middle-school teacher at Mira Vista Elementary in East Richmond Heights was arrested in the school parking lot Wednesday morning and charged with more than a dozen child sex-abuse crimes.

Ronald Guinto had been fired in November from Making Waves Academy, a Richmond charter school, after students came forward and asserted that he had abused them.

Inexplicably, he was then hired at Mira Vista and began teaching there in January.

When police, who were investigating the November charges at Making Waves, got wind that Guinto was teaching in the public schools, they realized they needed to act quickly.

Officials at the West Contra Costa Unified School District said Thursday that they ran the required fingerprint and criminal background checks and Guinto came up clean. However, they admitted that they didn't check with his previous employer because he had been a substitute teacher in the district and was already on the approved list.

Really? It apparently didn't occur to anyone to ask Guinto why he was suddenly available in the middle of the year or to pick up the telephone and call a school that is located in the same city.

The first remedial step here should be abundantly clear: The WCCUSD board must demand that reference checks be mandatory for all district hires. Period. The board should establish that policy immediately. No study committees or task forces are necessary.

Doing so in this case likely would have avoided embarrassment for the district and spared the kids at Mira Vista from what is surely a scary ordeal.

Administrators and personnel in Contra Costa schools must get the overarching message that protecting kids from preventable harm is every bit as much a part of the job as teaching them.