Cooking for Kids: Tuna and Mushroom Spaghetti

My oldest kids are big fans of the BBC TV series Masterchef.  Recently the BBC have started a children's one (Junior Masterchef) where kids aged 9-12 compete in daily cookoffs until one will be crowned a winner at the end of the series.  R (and A) have started using phrases such as "When I'm on Junior Masterchef..." and since they are both veteran cake makers I decided that R could help cook dinner so handed her  my cookbooks and this is the recipe R choose albeit with a slight adaptation to fit what we had in the cupboard.
 Tuna and Mushroom Spaghetti (serves 4)
350 g spaghetti
sauce:
2 tbsp oil
1 clove garlic, crushed
175 g mushrooms
tinned sweetcorn, drained
200 g can tuna in brine, drained
150-200 ml carton creme fraiche
juice of half a lemon
Cook the spaghetti in a pan of salted boiling water according to the instructions on the packet.
Whilst the pasta is cooking make the sauce.
Using a table knife cut the mushrooms into slices (nice and easy and no possibility of cutting little fingers!).
Heat the oil in the pan and add the garlic and mushrooms, cook for a few minutes until brown(er) and soft.  Add all the remaining sauce ingredients and stir to combine.
Once all the pasta is cooked drain and stir in the sauce.
Serve. Simple, quick and delicious.