School may be out, but math doesn’t have to take a break for the Thanksgiving holidays! Measurement, estimation, patterns, and geometry come in handy when decorating your home for the holidays. When the big day arrives math can make an appearance along with Grandpa, Cousin Sadie, and Great Uncle Fred. Many families like to start the day with a brisk walk or a game of touch football. Little ones can look for shapes and patterns while strolling through the fall foliage, or keep score at the family football game.
Another great way to keep guests entertained is to challenge them to a friendly competition while the turkey is roasting in the oven. My kids love building LEGO towers and bridges with their cousins, and one of their favorite challenges is to see who can build the longest bridge. Here’s how to organize a family bridge-building game that will leave everyone smiling (and practice a few math skills, too).
Divide the family into teams and hand each team the same number of materials. We like to use toothpicks and mini marshmallows (you can also use apple chunks instead of marshmallows). Kids will inevitably sneak a marshmallow or two to eat — just remind them that the more marshmallows they eat, the less building materials they’ll have for their bridge! For an extra challenge, throw in some large marshmallows and bamboo skewers or uncooked spaghetti noodles.
Provide a few restrictions on the final structure. For example, hand each team two or three pieces of paper and tell them that their structure can only touch the ground on those pieces of paper. Or limit the number of marshmallows that can touch the ground so that teams aren’t tempted to build a long line on the ground and call it a bridge. If you want to make things truly challenging, require each bridge to be able to withstand a set load, such as a roll of quarters or a paperback book.
Set a time limit. I’ve found that 15-20 minutes for a team of five gives enough time for the team members to collaborate, design, and build, yet still feel like they could benefit from a few more minutes. Keep everyone on their toes by announcing how many minutes are left every so often, then counting down the last 20 seconds.
Many kids will immediately begin stringing marshmallows and toothpicks together in a long line, or building a network of cubes…..then staring in dismay as their bridge sags in the middle. This is the perfect time to introduce them to basic structural engineering and geometry.
Help them see that triangles, when used properly, are the most stable and rigid shapes for construction. There’s a good reason why most of the world’s well known bridges, including Sydney Harbour Bridge, London’s Tower Bridge, New York’s Brooklyn Bridge, and San Francisco’s Golden Gate Bridge, all have triangles!
Each side of a triangle braces the two opposite sides, preventing them from moving in relation to one another: once the length of a triangle’s sides is determined, the angles cannot be changed. A square (or other 4-sided shape), on the other hand, can warp and skew. Test this by building a triangle with 3 marshmallows and 3 toothpicks. Stand the triangle up and press on one of the sides. What happens? Now build a square with 4 marshmallows and 4 toothpicks. Stand the square up and press down on the top. What happens? Note that you can strengthen the square by constructing a diagonal (use a 5th toothpick) between opposite corners.
One important note: preschoolers and toddlers will be eager to participate, but their older siblings may feel that little kids will end up hurting more than helping. Give the littlest ones their own stash of marshmallows and toothpicks to build their own structures (have a grownup present at all times for safety… toothpicks can be sharp).
This is a great opportunity for them to explore basic shapes. Show them the many shapes they can build with four equal sides… a square! A diamond! A rhombus, with an infinite variety of angles! Show them that there is only one shape they can build with three equal sides: an equilateral triangle. Can they figure out which shape is stronger? If the littlest kids still want to be involved in the main competition, give them a tape measure or yardstick and ask them to help measure the structures.
Once time is up, have everyone step away from their structures and begin the measuring process. The longest bridge wins! Award a fun prize to the winning team and make sure you take a photo of the winning structure. Regardless of who walks home with first place honors, the best prizes are sure to be family togetherness and fun math.