Boys' lightweight chino pant in straight fit

My son has been wearing this style of pants from Jcrew for the past several years, and as he is just about to grow out of his size 8 pair, I purchased the size 10. The waist was so big that I could have fit 2 of him in them. He is tall and thin, but then most boys his age are pretty thin. He is almost 9 and weighs about 70 lbs. He needed the 10 for length, but even with the adjustable waist all the way cinched in, they still didn't fit (and looked ridiculous). Would love to see some slim-sized options. Had to return them.

I bought two pairs for my son. They are made of a thinner material, which is perfect for warm weather. Also the material does not get wrinkly when they are machine-washed. I feel that these pants are more for dressing up with button down shirts.

These pants are really nice and work well for dressy occasions but are not at all suitable for a child who is a bit vivacious. They ripped on the third time my son wore them. He tripped and that was the end of his really good looking pants. Oh well. We bought another pair but now he has to change out of them before playing. Anything.