Egg rolling is a traditional activity, enjoyed across many cultures around the world. At Easter time, it is a fun way to explore these cultural traditions, while also developing understanding of friction and gravity. This simple experiment is great for encouraging good scientific practice while exploring two important scientific concepts.

## For these Egg Rolling Experiments, you will need

Whichever experiments you decide to undertake, always ensure to ask children to predict what is likely to happen. Asking why they predict what they do, and analysing whether or not they were correct, is a vital part of developing scientific enquiry skills.

Emphasise the importance of keeping all variables, other than the one being tested, constant in order to produce a fair test.

## Testing different types of egg

Test which eggs roll down the slope quickest and assess why this is happening.

• Set the ramp to a height of your choice
• Roll different types of egg down the slope from a set starting point, either all at once, or one by one using the stopwatch to time them
• Discuss which eggs travelled fastest, and why this may be. What distinguishing properties do these eggs have?

Test the impact of changing the gradient of the ramp by adjusting the top height.

• Choose a number of different gradients to test
• Choose one egg which you will re-use for each run of the experiment
• For each gradient, roll the egg from a set point on the ramp and time using a stopwatch
• Examine the time taken to roll down the ramp when set at each gradient – do you notice a pattern?
• Why might this way of measurement be unreliable?

Testing different ramp coverings

Test the impact of changing the covering of the ramp and assess reasons for the differences

• Set the ramp to one set height and choose one egg
• Use a variety of coverings on the ramp, including the two sides already attached, and measure the time it takes the egg reaches the bottom with the stopwatch
• What are your results, and what possible reasons for them can you think of?
• Are the eggs bouncing rather than rolling? What impact could this have?

## Theory

These experiments all look at the role of friction and gravity in affecting the speed of the eggs.

Gravity is the force which causes objects with mass to be attracted to one another. Such is size of the Earth, and the relative weakness of the gravitational force, the pull towards the ground is the main observable example of gravity. Gravitational acceleration is the same for all objects, but the impact of air resistance means that heavier objects are able to fall faster than lighter ones.

Friction is the force which provides resistance to moving objects. This slows moving objects down, or reduces their rate of acceleration. Smoother surfaces provide less friction than rough ones, and is a key consideration in choosing which materials to use in all sorts of situations, from road building to making children’s slides.