Housemates' human clock
The housemates were tasked with creating a human clock this afternoon (3.15pm).
For the test - which is part of this week's The Test of Time 'Big Brother' shopping challenge - the group had to form a clock by standing on markers in the garden and then each estimate when five minutes had passed.
The aim is for the group to collectively estimate one hour. In order to pass the test they cannot be out by more than two-and-a-half minutes either way.
Head of House Dale was called to the Diary Room to receive the instructions
Dale read: "Each Housemate will have to count five minutes in their head and shout 'time', then the next housemate should start their five minutes - the last person should shout 'bong'.
"Housemates are not allowed to tap their feet or hands or nod to help them keep time - they are not allowed to assist other housemates or they will fail."
As Head of House Dale was not permitted to join in the task, and the group had to perform the challenge in silence.
The contestants made their way into the garden - where they had to stand in a circle to form the face of a clock - and found headbands with numbers on which they must wear.
Noticing the headwear, Luke said: "We look like giant candles on a birthday cake."
Dale took his role as leader very seriously, and set about reminding the group to "keep silent and concentrate" as they got into position.
He added: "Try and stay focussed, guys. Don't start messing about."
As the task got underway all the housemates seemed to be concentrating hard.
However, fourth-in-line Kathreya got into a pickle and miscounted, prompting Stuart and Rex to exchange worried glances.
© BANG Media International