Diogenesister, I am excited you might tell your kids about my financial advice!
If I recall correctly, you are in the UK?
Change the amounts! Tell your kids to start saving £175 per month starting at age 20 or whenever they start their working life. After 45 years they should have a nice nest egg of around £350,000.
This is assuming an annual return of 5% interest. All of this can vary, that's why they need to Google "compound interest calculator" and play with the inputs. I don't even have a favorite one saved. I just Google it each time and quickly pick through the multiple options for one that looks user friendly to me.
Give them the task of figuring out how much they would have to save/invest monthly to be a half millionaire. Could they save more? Work longer? Invest more riskily for a greater rate of return?
Ask them how much money they would need to EARN to be able to put that amount away in an investment and forget about it until retirement. £175 per month is £2100 a year. Could they find a job making an annual salary of £25,000 a year? That's less than 10%! What if they found a better job? They could either put more away or have a greater amount to live on.
What kind of schooling will they need in order to get the job they want? This is what every young teen should think about! Are you taking the right classes? Are you studying hard enough the pass the exams you need to get the job you want? How is your schooling going? Have you tried, failed and learned something about yourself and your learning abilities? What else can you do that plays to your strengths?
This is what teachers call "backward mapping." There is an end result that you want your students to master. So, you back up through all of the previous skills you need to master in order to get there, and you start teaching at the beginning.
Ask your kids to backward map retiring a half millionaire. Start out by telling them it's not impossible or even particularly difficult at all given they are able to hold onto a modest paying job. Let them dig into the subject on their own. Ask the questions above to keep them going. Good teachers ask, not tell.
If they love the subject, give them a bonus/extra credit question: what if you want to retire a millionaire? How much harder would that be?
The key to keeping kids interested is making it applicable to their lives. Ultimately, it should come down to their schooling right now. Are they studying the right things to help them get the job they ultimately want? How is their studying going? It's okay if becoming a doctor is not in the plans. I knew way before high school my son would not be able to handle that academically or emotionally. The end of each term gave us more information, though. His passions and hobbies gave us more information. He loves mechanical things, did well enough at community college to know he could handle university level work and had the work ethic. He's now going to the University of Maryland in the autumn to study engineering. If he had struggled in community college, we would have stopped with an Associate's degree and found a career path for that amount of training.
Oh dear. I'm going to shut up now. I guess I miss teaching and find myself creating curriculum in my head. I have loved raising my son and still enjoy steering him academically. I can tell you love your kiddos, too, and want the best for them. You're doing great. You aren't raising them JW and neither am I! These kids will have great lives, I know it!