Caps Ridge Trail
3.8 miles round-trip
1,800 feet of elevation gain
Here's a report from a 2015 hike Sage (my sister) and I (Alex) did of Caps Ridge Trail. Caps Ridge is quite an adventurous trip -- and the summit of Jefferson is just a few rocky tenths of a mile away once you're above the Caps. Below are some pictures from our trek to give you a sense of the difficult and fun terrain. The pictures were taken from my mom's post of the whole hike which you can find here if you're interested.
The terrain starts off in the trees, then becomes rocky and even more rockier and much steeper as you continue along. Once out of the trees (one mile from the parking lot), you'll soon reach the first of three "caps." Each "cap" is a climbing/rock scramble. You will be above treeline and exposed to all weather for all the caps (and for the continuation to the summit of Mt. Jefferson, if you choose to continue onward), so make sure the forecast is for excellent weather, and make sure you have layers, lots of water, and the Ten Essentials with you.
Be careful on some of these sections! As you can see, it gets very, very steep.
There are some old videos of Sage climbing parts of the Caps back when she was 5 years old on this post -- - https://sagehikes.blogspot.com/2010/08/mt-jefferson-4k-2-august-29-2010.html. That trip report will give you a good idea of how very young (and enthusiastic) kids can handle these kinds of scrambles (with a parent or caregiver spotting them), and it also shows how high up you'll be while climbing.
Once above the Caps, you can continue to the summit of Mt. Jefferson, a Four Thousand Footer (and two mountains over from Mt. Washington).
You'll have a great time hiking Caps Ridge Trail!