Fastening is how engineers join pieces together, and different fasteners are best for different jobs. Glue creates a strong bond between surfaces but takes time to dry and is hard to undo. Tape is quick and easy but weaker than most other methods. Screws clamp pieces together with strong, removable force. Nails are fast to drive but harder to remove. Engineers choose fasteners based on the materials being joined, how strong the joint needs to be, whether the joint needs to be taken apart later, and how quickly the project needs to be assembled.
Set up testing stations: have students join two craft sticks using different methods (white glue, hot glue, masking tape, duct tape, rubber bands, paper clips, brads). After the joints dry, test each one by pulling the sticks apart and rating the strength. Then discuss: which joints are permanent? Which are removable? Which were fastest to make? Have students match fasteners to scenarios: "You are building a birdhouse that will be outside in the rain — what fastener would you use?" This builds the habit of choosing fasteners thoughtfully rather than grabbing whatever is closest.
You have measured and cut your pieces. Now you need to join them together. The way you connect pieces — called fastening — is just as important as the pieces themselves. A structure is only as strong as its weakest joint, and choosing the wrong fastener can turn a great design into a wobbly mess.
Tape is the fastest option. Stick it on and you are done. But tape has real limitations. It weakens over time, especially in heat or moisture. It does not grip irregular surfaces well. And it is not very strong compared to other options. Tape is great for temporary connections, quick prototypes, and light-duty jobs — holding a poster to a wall, bundling papers together. For anything that needs to last or carry significant force, you need something stronger.
Glue creates a permanent bond by chemically adhering to both surfaces. White school glue works well on paper and wood but dissolves in water. Hot glue sets quickly and bonds many materials but can be brittle. Wood glue creates very strong, water-resistant bonds on wood. Super glue bonds almost anything but is permanent and unforgiving — you get one chance to position the pieces. The general rule with glue: a thin, even layer on both surfaces is stronger than a thick blob on one surface. Press the pieces together firmly and hold them until the glue sets.
Nails are metal pins hammered through pieces of material. They are fast — a carpenter can drive a nail in a few seconds — and they hold pieces together through friction between the nail and the surrounding material. Nails are excellent for framing houses, where hundreds of joints need to be assembled quickly. Their weakness is pull-out resistance: a nail relies on friction, so a steady pulling force can gradually work it loose.
Screws have spiral threads that grip the material as they are driven in. This threading gives screws much greater pull-out resistance than nails — the material has to break around the threads for the screw to come out. Screws can also be removed and reused by turning them backward. They are slower to install than nails but create stronger, more precise, and reversible joints. Furniture, decks, and cabinets typically use screws.
The engineering skill is matching the fastener to the job. Ask: How much force will this joint face? Will it need to come apart later? Will it get wet? How fast do I need to assemble it? What materials am I joining? These questions point to the right fastener every time.