In class Mrs Waller helped us to work out six variables that plants need:
We discussed how to prove that these variables were essential for growth and decided to plant three carrot seedlings for each variable, giving each seedling differing amounts of that variable. For instance, the group that was testing for the necessity for water would plant one seedling with no water, one with a little water to keep the soil moist and one with lots of water.
We measured the height of the seedlings at the beginning of the experiment and labelled each one to show the variable we were measuring and the height in centimetres.
Here we are preparing the pots: