Pyramids of number, biomass and energy
I have finally managed to sort this out! The original document wasn't the right one. There are 2 resources - one for less able students which only requires a pyramid of numbers and the second for more able. The numbers of organisms are included as are the trophic levels. Pondweed may not be on the list, but my pupils recognised this as a producer and hence trophic level 1. Just add graph paper, scissors, glue and calculators.