Open the bonnet, there will on most cars be a release lever you will need to pull from within the cockpit first, and then there will be a secondary catch under the bonnet to fully release before you can open it. Then point out the engine oil dipstick. Then explain that you would check the oil on a regular basis, particularly before starting a long journey. You should check the oil when the engine is cold and the car is parked on a flat level ground. Check it by pulling out the dipstick and wiping clean, then re-dipping and checking the level against the minimum and maximum markers on the stick. Once explained ensure bonnet is FULLY closed.