This was a complex challenge to solve with a number of parts to it.

Thank you to everyone who submitted a solution, or part solution.

Here are those that showed solutions to many or all of the parts of the challenge.

Firstly, Class 2 from  Goodleigh School in the UK sent in this contribution:

First we put all the names into a tally chart by going down the list one by one.
Then we put the tally numbers into frequency order.
It looked like this:
A=$6$  J=$5$  B=$3$  D=$3$  H=$3$  P=$3$   S=$3$  T=$3$  M=$2$  N=$2$  W=$2$
Then we looked at the chart and we saw that there was a T missing,So we knew that Tessa was away.In the block graph the letters were: JMNPS
                                                        

Next we have Daisy and Rosie from  St Nicolas Junior School, Newbury UK who sent in these two pieces of work:

Lastly this came from Eliza at Moonee Ponds Central Primary School  in Australia.

We can only include a small part on this page, as she sent in a big file. You can look at the whole file here .