Time needed: 1 to 5 min
Why? Students, teachers and classroom need to relate school to real life. Everyone has different mental representations about an object, if you show it, you can share it. Book-pages are 2-dimensional, but objects are 3-dimensional. They have a shape, they give you a feeling when you touch them, and sometimes they smell. Things attract many senses, so by using them it is a lasting way to teach and learn.
When? Whenever you can bring an item and show it to students, do it.
How? Bring an item, and show it when you need it. Let it pass through.
Any risks? No risks to but big affect. Small risk for breaking and distraction, when the object passes through the students.