The rush to digital devices in American classrooms is making students dumber every day. I was reminded of this while re-organizing my desk drawer to find a secure place for my slide rule.

Many readers would respond: “You still use a slide rule? We’ve had digital devices with ‘log’ keys for decades!”

And that is the point. For two decades now, most students come to college without the least idea what a logarithmic scale does. They just punch the ‘log’ key on a calculator and accept the answer. Only if students hold in their hands a logarithmic scale, where the distance from 1-to-10 equals the next distance from 10-to-100 and the next from 100-to-1000 can they begin to understand logarithms.

Only by manipulating a slide rule can they come to understand that you can multiply by adding and divide by subtracting. That learning comes as much by “feeling” the manipulations you make with the slide rule as it does by any abstract words or text.

For a time in the 1990s, it appeared we would lose another important experience: the circular clockface with hands. Many time pieces on our wrists and on our walls are now digital, flashing their square-block numbers. But enough analog clocks remain in our children’s environment that they still get to learn the big hand is minutes and the little hand is for hours. It can help understand base 12. But the most important lesson is the clock hands move “clockwise.”

Take away the analog clockface and we take away our students’ only definition of clockwise. Tornadoes rotate counter-clockwise in the northern hemisphere, clockwise in Australia. But that statement becomes absolutely meaningless if all of the clocks in a student’s experience are digital.

Then there is the lever. We might pry up a lid on a paint can or use a screwdriver to pry up a nail. But for a real thought-filled understanding of a lever, the best example is the teeter-totter. Older generations of students learned to adjust the board across the pivot point (fulcrum) to balance a heavier playmate with a lighter one. And we learned that when the fulcrum was off-center, the lighter playmate went higher. That valuable educational experience is now gone from our playgrounds. Perhaps someday we will enclose every student in a protective bubble — and they will learn nothing.

The counterargument is the concepts of logarithms, clockwise and leverage can all be learned on those ever-present, square-cornered devices in students’ hands. But those are abstractions and pictures of abstractions. Every minute a student spends with neck bent at 60 degrees immersed in their digital devices is a minute they no longer are experiencing the real world. And it was the real multi-sensory experiences with the real world that built meaning. But today, our students are desperately falling behind in these very skills based on experiences — hands on, genuinely interactive, real consequence, test-truthful experiences — that digital devices do not provide.

Schools in China do not make this mistake. For the most part, they do not allow calculators and other digital devices into the classroom until middle school. And then, the use of these devices is strictly limited. Students can take square roots and do log equations without ever hitting a key on the calculator.

The result is that today the majority of terminal degrees in engineering and physics at U.S. universities go to foreign born and educated students who were kept away from digital devices when young. Teckies agonize there still are regions of rural America that do not have broadband access and they fret over the “digital divide,” the haves and have-nots in digital technology. Ironically, it is those rural students who grow up with a hunting knife or multipurpose tool on their belt, rather than a smartphone, who are making up the backbone of our organismic biology students who will work for fish and game divisions and in conservation fields. In these areas, the advantage to the “digital divide” lies with those who are not constantly distracted by video games, virtual unreality and hyper-society.

It is past time to put slide rules and analog clocks back into our classrooms, and teeter-totters back on the playground — and shelve the expensive digital toys.

John Richard Schrock is a professor in the Department of Biological Sciences at Emporia State University.