there isn't a really good answer to this. you could use a container that he could open, however, the strips go bad pretty fast from humidity. The container from the manufacturer has a dessicant liner designed to remove humidity. If the strips are exposed to humidity for a few hours they will be very inaccurate. I would guess 50% RH or higher can ruin them. if it's very cold (below 40F, all day) where you live and your house doesn't have a humidifier, then the strips may stay good for a longer time in any container.
You can't just put 3 strips in an old vial because the dessicant liner also goes bad. You could put your own dessicant in a easier-to-open vial but wow, it's a lot of work for you and he'll be big enough to deal with the stips before too long, maybe even now with practice.
maybe put spent strips in an old vial han have him figure out a way to hold and open the container without spilling them. cheers and good luck.