1. Gears

• Encourage students to use an actual bike and count the teeth on the cogs for this task.
• You could encourage students to investigate other places where cogs / gears are also used. They are usually hidden and students may not be aware of how they work in clocks, watches etc.

2. Shadows

• Students will need to choose a sunny day for this task.
  Logistically, this task could be hard to coordinate at different times of the day so you might want to limit it to finding if the ratio of height of object to length of shadow ratio is about the same for all objects at a particular time of the day.
  Note: You can tell the time using shadows but it is complex and is a different calibration for each day/month of the year and depends on your longitude and latitude. There is plenty of information about this on the internet if students want to learn about it.