If Positive Controls Fail, Is Fair Project Usually Repeated?

[Chili]

Although this has not occurred (yet) as my child started growing bacteria today, what would happen if a child did his project and even the three positive controls failed? (I watched him swab his bacteria and wonder if his zig zags were too far apart when using a zone of inhibition to measure. ) Would he/should he need to do the project again or just state what he thinks happened? Thanks. We're getting ready to go on a vacation and I'm wondering if people do their projects over for their fairs if things don't turn out. I can't wait to see some bacteria grow and have his project be successful so we can think of other things around the holidays. Thanks again and Happy Holidays to each and every one of you science experts!

[tdaly]

It's really up to you. IF the bacteria don't grow, your child can choose to repeat his/her experiment or choose to report that nothing grew. Either way would be just fine. The most important thing is that your child doesn't make up or fabricate anything. If nothing happens, just say so. Failure is part of science.

Some people do their projects over and over again, refining techniques and looking for new data. Others don't. The most important thing right now is not the science fair project (your child will have plenty of opportunities to do them), but the holidays. If your child's project is ruining your vacation/holidays, then don't worry about re-doing the project.