Geared crank fan design challenge (Grade 4)

Grade: Four

Topic: Understanding structures and mechanisms (pulleys and gears)

Students will research, design, and build (using the materials and tools provided) a geared crank fan. The gears must be arranged so that they are driven by an elastic fan belt, and the fan rotates faster than the crank. The fan can be hand held or stand on a flat surface. Students will record their results, make modifications and re-test (if time permits), and complete a report on the steps they took to solve the design challenge.

OCTE 2012 – Elementary Conference Workshops

Crank fan example


  • CSA approved safety glasses/goggles, one pair per person (parent volunteers included);
  • an approved eyewash station; this can be two eyewash bottles containing approved eyewash fluid that has not reached its expiry time limit after decanting, or an installed system (an actual eyewash station, or approved faucet attachment);
  • a first aid kit (please see your Board's Health and Safety Regulations if one is being purchased for your classroom);
  • basic hacksaws (junior saws), or coping saws, minimum one for every 3 projects
  • bench hooks, minimum one for every 3 projects
  • 3" C-clamps, minimum one for every 3 projects
  • a ruler, one per project;
  • to make a crank by installing a piece of dowel in the 74 mm MDF wheel, the following tools are needed;
    • manual hand drill (closed, non-powered), 3 per class
    • drill bits 5/32", or the size of your dowel, one for each drill
  • hammer, one for every 3-5 projects (used with nail holder and finishing nail to start holes for screw eyes),
  • corrugated cardboard strips with a split in the end, one for every hammer that is made available; this is used to hold finishing nails at a safe distance from the students' fingers
  • scissors, one pair for every project (students may supply their own);
  • low heat glue guns (one for every five projects); please note that white glue can be used instead of glue guns;
  • work gloves, 1 pair per low heat glue guns
  • aprons, 1 per low heat glue gun.


  • basswood strips 24" x 1/2" x 1/2" (12mm x 12mm x 61cm),, 3 per project,
  • 5/32"(4mm) hardwood dowel (, 12" (30 cm) per project,
  • screw eye holders 9/64" (, 4 per project,
  • 50 mm pulley with 4mm hole (, 1 per project,
  • 25 mm pulley with 4mm hole (, 1 per project,
  • 74 mm MDF wheel with 4mm hole (, 2 per project,
  • triangle card stock gussets 10-12 per project
  • sand paper, medium to fine grit, 1 sheet for every 5 projects;
  • long elastic bands , 1 per project (connects gears/pulley wheels);
  • 1 roll of duct tape, for the class;
  • finishing nails, one small package;
  • found materials, to make fan blades (e.g., pop bottles, plastic jugs, cereal boxes, cardboard, etc.); the teacher must approve of an item before a student is allowed to use it;
  • low heat glue sticks, one per project; if using white glue, have about 300ml on hand for the class;