Building Bridges

Grade 7 Science No Comments »

My grade 7 students will begin building bridges next week. They will be allowed to use white glue and wooden sticks of their choosing, such as popsicle sticks, toothpicks, and stir sticks. They will model it after a real bridge that exists somewhere in the world, and so a research component will be involved. They will have to meet the following design specifications:

  1. The bridge deck must be able to span a distance of 30cm but may not be longer than 40cm.
  2. The bridge must be able to carry a load of at least 1kg.
  3. The bridge can be no higher than 20cm off the ground.
  4. The travelled portion (width) of your bridge must be at least 3cm wide, capable of transporting a Hotwheel © or Matchbox© car (each car’s dimensions are approximately 30 mm wide x 70 mm long x 25 mm high).

The following websites will help them as they prepare to build their bridges:

Bridge Building page from 42Explore

Physics Balsa Bridge Building Contest – scroll down to the links at bottom

In addition, they can also explore the following bridge building game sites:

Smart Kit Bridge Building Game

Nova Build a Bridge

Have a great week.

Playing with Mechanical Advantage

Grade 8 Science No Comments »

I have finished discussing the basics of simple machines with my grade 8 classes. We have looked at the formula for work, and their weekend homework task was to play on and explore the following websites:

Edheads (update – this game is no longer free, it now requires membership)
Museum of Science and Industry

This week we begin mechanical advantage.  We will start by playing with levers (materials: prisms for fulcrums, metre sticks, spring scales, and various masses). The students will investigate what happens to mechanical advantage as we change between first, second and third class levers, exploring with various lengths of effort and load arms. We will then move on to pulleys, and the students will build various systems with fixed and movable pulleys (materials: pulleys, string, spring scales, various masses, and retort stands with ring clamps). They will explore different lengths of rope and how mechanical advantage changes depending on how the load is supported.

Here are some links that I will use along the way to supplement their learning:

Wisc Online – I will have to tread carefully with this one, as the units are not metric.

Pulley Basics (from an unexpected source: Summerlift Products)

Videos:
Mechanical Advantage (from Hila Road Outdoor Centre & Educational Resources)
Eureka Video Series (1980’s cartoon series from TV Ontario) – This is the first video in the work and mechanical advantage series, which include episodes 8 through 15. For more information on Eureka, see the Wikipedia Page.
Mechanical Advantage (from Khan Academy)

If you have any other good resources, I would love to see them.
Have a great week.

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