Will these bags be big enough to carry my school book in for high school?

yeah they are fine! at my school, we make fun of the freshman with the "freshman backpacks"aka the ones who look like turtles.. haha.. but that is adorable! i love yellow. i had a bag smaller than that, just like a little tote my first two years of high school (im a juniorr) and they worked fine, locker or no locker, but lockers definitely help :)