I teach economics in Germany, and I’ve had the growing impression that many students struggle more than they used to with abstract structures if I only explain them verbally or symbolically.
So now I’m teaching topics like shares and subscription rights in 12th grade with Lego bricks.
It sounds silly at first, but it actually helps.
Once the capital stock, the old shares, the new shares, and the changed ownership ratios are physically visible, quite a few students suddenly understand what they could not grasp in purely abstract form.
I’m not even sure whether the problem is “less abstract thinking” in a strict sense, or whether many students now simply need a stronger concrete bridge before they can move into abstraction.