Scientist Nina and her young experimenters discover the amazing ways that things can change and react in our everyday world. Nina investigates why we get sleepy dust in our eyes with the help of Luke, her sight neuron. Experimenters Daniel and Luke visit Nina in her lab and use their senses to work out that sleepy dust feels gritty and hard. Nina does an experiment to show us that our tears aren't just plain water - they have special cleaning salts in them. Then they all go to the countryside and do some muddy off-road driving. They find out that our eyelids are a bit like windscreen wipers! Finally, back in the lab, the Experimenters use Epsom salts to make tiny crystals that feel just like the sleepy dust we find in our eyes after a big sleep.