A game for primary aged children and beyond - Nim

Can you work out a strategy to always win if you take the first move?

Nim - A game for 2 players

Put 7 counters in a pile Take turns to take 1-2 counters from the pile The player to take the last counter in the pile is the WINNER

Once you have mastered Nim with 7 counters, experiment with a different number of starting counters - can you still always win if you take the first move?