They will pick out the tinier pieces in there, you can also mix in some corse sand. Mine are now eating the larger pieces of grit at 3 months old. They used to sell chick grit but it is impossible to find anymore around here so I went with sand and regular grit.
Not necessarily true. I have 12 chicks that are 1.5 weeks old and are being raised by hens and they are eating everything their moms find for them in the run. They need grit. They have access to chick feed, but are also eating grass, weeds, bugs and other things.
i crush the grit a little smaller to give to my 4 week old chicks and give it to them when they are getting treats other than chick starter.
i used what i had around and found the priority mail envelopes the easier to use...put some grit in the smash with hammer. i then used 2 old yogurt cups i had and made a sieve out of one cup so the smaller pieces fall into the cup below and i feed the smaller pieces to the chick...like the size of course sand.
i make the holes larger as the chicks get bigger so i can get bigger pieces.
When I first got grit for my group, I bought that kind as well. Then I noticed it said on the bag not to give it to chicks until they are at least 8 weeks old. I didn't want to give it to them because it looked too big as well so I went back to tsc. I spotted a bag of chick grit in a different area than the poultry grit which can be used for smaller/younger chicks so I got that for them. I also use sand in a dust bath that they peck at as well.