It's difficult to understand if you teach according to the textbook.
It's difficult to understand if you follow the textbook.
You should change the approach.
It's difficult to understand if you teach according to the textbook.
わかりにくい= difficult to understand
教科書通り= according to the textbook.
It's difficult to understand if you follow the textbook.
教科書に沿って=follow the textbook.
You should change the approach.
アプローチを少し変えて教えたほうがいい。
上記を組み合わせるとつたわると思います。試してみてください。