Architecture: It's Elementary
Put out by the Architecture Institute of and the Michigan Architecture Association, this amazing book contains lesson plans and activities for kids from kindergarten through 5th grade. Many can be adapted for festivals or for fun at home.
Download book here: http://www.k5architecture.org/Download_chpt.htm
Building a House
By supplying a large number of smaller building supplies (hammers, nails, drywall, paint, concrete sample, lumber, electrical wires, plumbing, furniture) a discussion about the best order to use them to build a house can ensue. This would obviously be a simplified version, but can get the children thinking and provide insight about building structures.
Building Block Towers
Using simple 3-D blocks, children can explore architecture and creation, especially when specialized blocks such as arches, columns, triangle roofs or semi circles are included. Blocks can help develop a sense of spatial relations and shapes.
Using construction paper, children will explore and recreate the design features specific to castles and consider other architectural examples with specific functions.
Activity courtesy of Dick Blick.
Earthquake-Proof Engineering for Skyscrapers
Using a 3-ring binder, several rubber balls, two rubber bands and a large lego baseplate, you can create a shake plate for testing the stability of lego skyscrapers. Children can compare the difference between towers of differing heights and base size and discuss other ideas to improve building stability.
See full activity here: Scientific American: Bring Science Home.
This series of lessons and activities developed by PBS/WGBH explore large structures and what it takes to build them. A myriad of activities suitable for festivals can be found on the Website. In addition you'll find a series of short online challenges that has kids choose the best design for bridges, domes, skyscrapers, dams, and tunnels in different environments. If the online format is inconvenient, BUILDING BIG can be purchased from Shop PBS.
Find the educational materials and try the challenges at Building Big.
Using spaghetti and marshmallows or gumdrops, children can create whatever type of structure they desire. Topics of discussion can include structural elements, design features, etc.
Using a single sheet of square paper, children can create a small paper house to decorate. Discussion can center around window/door features normally incorporated, roof design, building materials, etc.
A video demonstration is located here.