Agree with OB about using the CRP-5, however to be pedantic the QNH is given as it technically gives slightly more accuracy as you can work out pressure altitude and a more precise temperature. You should notice in the calculation that this altitude precision cannot be used as the scales are too small, but it does affect the temperature by 1°.
Taking minimum flight altitude of 15,000 feet, the pressure altitude would be 14,730 feet (reduce by 270 feet for the 10 HPa drop to 1013 HPa). ISA temperature -14°C, so OAT is +1°C (you'll get -15°C and 0°C if you use 15,000 feet, and make very little difference to the final answer!).
In the "Altitude" window there is a temperature scale to match against the altitude scale. Match +1°C against 15,000 feet (see, I was being really pedantic, and am using 15,000 because the scale cannot be read to 270 feet). Read from true altitude of 15,000 on the outer scale to just over 14,000 on the inner, say about 14,050 feet. You get about 14,100 if you use 0°C.
That is how I would teach it too, although I make sure the students know the formula so they can choose.
Send Clowns
Gen Nav
BCFT
P.S. The reason for the pedantry is really for consistency. It should not affect this answer unless the question ask for more precision than is fair, but it keeps you thinking about what reference your altitudes are in!