Not everything online is evil, nor does danger lurk behind every new app that comes to market. But keeping up with your teens’ and preteens’ online activities is much like trying to nail jelly to the barn door – frustrating, futile and something bound to make you feel inept.

Keep in mind that no app poses a danger in and of itself, but many do provide kids with an opportunity to make, ahem, bad choices.

1. Audio Manager.

Sometimes when it walks like a duck and talks like a duck, it’s really not a duck. Such is the case with Audio Manager, an app that has nothing to do with managing your teen’s music files or controlling the volume on his smartphone and everything to do with him hiding things like nude photos from you. It’s one of the top apps for hiding other apps.

Yes, there are such things. Kids can hide any app they don’t want you to see, Teen Safe says. When you press and hold the Audio Manager app, a lock screen is revealed — behind which users can hide messages, photos, videos, and other apps.

2. Calculator%.

Same deal, but this time with a calculator icon posing as something it isn’t. Sedgrid Lewis, online safety expert, notes that these apps look like a normal calculator app but when teens push a button within the app they can hide all inappropriate pictures. “It’s a key way teens are hiding their nude pictures from their parents,” said Lewis.

Lewis says the best way to solve this situation is for parents to add their teen to their iCloud account. That way, whenever a new app is downloaded by the teen, it will automatically download to the parent’s phone as well.

Think it’s not serious? Last fall, there was a headline-making case in a Colorado high school where teens used apps to hide a huge sexting ring from parents and school officials. And an Alabama district attorney, Pamela Casey, posted the video below to warn parents about the Calculator% app.

3. Vaulty.

Vaulty will not only store photos and videos away from parental spying eyes, but it also will snap a photo of anyone who tries to access the “vault” with the wrong password. Parents who find it on their teens’ phones can conclude just one thing: Your kid is hiding things from you.

– Ann Brenoff

Read more: The 12 Apps That Every Parent Of A Teen Should Know About

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