what is a good laptop for my teenager

I suggest starting by looking at these articles to help narrow down your choices:

• Mac - Compare Models - Apple
• MacBook Air vs. MacBook Pro: how Apple's laptops compare - The Verge
• MacBook Air vs MacBook vs 13-inch MacBook Pro. Which of Apple's small laptops is right for you? - Macworld

If the goal is to only use this notebook for general homework use and Internet surfing and not for graphics-intensive apps, then either the MacBook Air or MacBook models should do nicely. In this case the MacBook Pro would be a bit of an "overkill."

Some suggestions to consider:

1. Be aware that some models do not allow you to upgrade hardware, like RAM or drive storage size, so it's important to order it with what you believe should be required and leave some room for requirement growth. Of course, any of these upgrades will add to the cost.
2. If cost is an issue, you will be limited to which models can be had for less than $1000. You would have to look at non-Apple laptops for this. However, another option is to get a used notebook. Both Apple and a number of third-party sources are available for this. A couple of third-party sources, I would suggest, are: Other World Computing (OWC) & Mac of All Trades.
3. Do consider getting an AppleCare+ plan. This will extend the 1-year Apple Hardware Warranty for an additional 2 years and will make a difference should any repairs be required. In addition, you should be aware that typically Apple will only repair the device in the same country as where it was purchased. This is not a "hard" rule, but it could apply and negotiating with Apple is your best course of action should the event occur when you need help.