Happy birthday William

Today was Williams 6th birthday so learning today was all based around birthday helium balloons. Why do they float? How many balloons will it take to lift a bottle? How many balloons would we need to lift each of us? Does spreading the weight out evenly in the basket mean the balloons can lift it more easily? What is the highest value of coins that the balloons can lift? If the room was warmer, would the balloons be more or less floaty? ... and a whole load more questions! Lots of fun and learning all from some helium balloons and coins as weights.