Let's start with a picture of this year's finished Box Tower. There are two boxes. One is tall and the other is a rectangular box which serves as a base. The tall box is embedded in the base box.
First, I place the tall box on top of the base box so I can trace its bottom dimensions onto the base box. The tracings mark the square I will cut so the tall box will fit into the base box.
I cut out the square on the base box. As you can see below, there are inside flaps that the utility knife does not cut. Those inside flaps are important for the strength of the box, so I do not remove them.
Rather, I notch the inside flap so it matches the opening and then I tape it to the top piece of cardboard thus increasing the structure strength at this level.
Since I have the opening in the base box, I tape down the flaps on the bottom of this box. They are easy to reach at this point in the construction. One reason to tape the flaps on the bottom down is to give the box strength. In addition, by taping those flaps down, the medium---sand or whatever---will not get caught under those bottom flaps.
I trim the flap so it does not hang over the edge because when I drop the tall box into the base box, the flap will fit inside the structure. I then tape the edge of the flap to give it strength and tape the bottom flaps of the of the tall box.
Before dropping the tall box into the base box, I cut holes in the bottom sides of the base box to correspond to the holes of the tall box. Again, the hole is only cut on three sides so there is a flap the comes out. These flaps that fold down and out from the holes are important because they are used to tape the box down firmly.
When the tall box is dropped into the base, an inner chamber is formed. At this point, the flap of the tall box is taped to the bottom of the base box making it firmly attached to the base box.
With the tall box inside the base, I cut a hole in the tall box where it meets the base box. The hole is only cut on the top and two sides. At this point I have not taped the top of the tall box so I can reach in and push out the cut hole out from inside so there is a flap again.
I tape the new flap to the top of the base. By doing that, the embedded box is secured for a second time onto the base box.
I make one more cut on top of the tall box. Since children will always find the highest level of any apparatus, it is important to have a hole on top for them to drop things into the Box Tower.
The box tower is now ready to be taped to the table. I use the flap from the bottom hole to offer more surface for taping the structure securely to the table . Tape is also used all around the bottom of the apparatus.
Here is another view of how the sides of the base box are taped to the table.
Now for the provisions. This year I used wood shavings that a parent donated. I also added farm animals. The invitation to play is complete---and strong and secure.
If you want to see another version of the Box Tower, check out Box Tower 2. This version is also strong, but built differently.
My hope is not that you build the exact same Box Tower. Rather, take the ideas for connecting and taping the boxes together to make your own apparatus strong and secure. When you start to build, you will see there is no one way to put the elements together. The fun begins when you connect the properties of the materials with your imagination.