How did the Allies win WWI?
The Allies "won" World War I by simply outlasting the Central Powers. Germany was fighting a two front war for most of the conflict, an was bled by a long, grinding, attrition style of trench warfare that took millions of her young men. When the United States entered the war in 1917 on the Allied side, it was fresh, with a huge industrial base already manufacturing war materiel, and a population unbloodied as of yet. There was no way Germany could have competed long term with America allied against her.
Specifically, Germany failed to conquer Paris in the final 1918 offensive, in large part due to the presence of American troops. Germany's economy was bankrupt and teetering, its reserves of manpower exhausted, and it was forced to sue for peace.
Basically, the Allies won the war by holding on long enough for the US to enter the war. This is not meant to imply that somehow we were better than them, but the weight of US soliders, coming when the two sides were so equally balanced, tipped the scales to the Allied side.
The Allies managed to stop the German advance at the beginning of the war. Then they started in on the trench warfare. By doing this, they held the Germans in check until the US was persuaded to join the war. This put so many fresh soldiers into the war that it made the difference.
America's primary contribution to victory by the Allies in WW1 was economic / industrial means. The weight of US military effort was almost inconsequential to the outcome. Germany was not exhausted by 1918 but boosted by the collapse of Russia. They very nearly defeated the Allies in March 1918 with Australian and Canadian forces playing significant roles in 1918 in forcing the defeat of the Germans in 1918 not in 1919 as most Allied leaders including US President Woodrow Wilson believed. The Germans were defeated by August 1918 and yes their home front was collapsing but this is viewed in hindsight and not at all apparent in early 1918. The Americans played NO role in halting the 1918 offensive and the lack of awareness of your own country men's achievements during the 1918 crisis is staggering - especially as you are supposedly educating the children of those men we vowed to 'NEVER FORGET'.
Germany lost the war for many reasons including two key factors;
1. The economic capacity of Germany was limited by blockade and geography which favoured the Allies in a long war.
2. The Allies developed tactics that best utilised new technologies such as tanks, aircraft, artillery technology, use of light machine guns, better logistical planning and communication methods that allowed more decisive offensive manoeuvre. This defeated the German Army in the field and had it in full retreat by September 1918. This was about speed of learning and adaptation which is always a factor in warfare. The Allies learnt how to win before the Germans. Note these were the same tactics the Germans applied to Europe in WW2.
For those teaching our kids, I'd suggest knowing what role Australians played on the Western Front in 1918 as it surely is our finest military achievement and will improve the accuracy of the information you're imparting.