Bushnell Excursion 8x28
also Pentax papillio, 6.5x or 8.5x
Compact roof-prism binoculars like the Bushnell mentioned here, and reverse-porros like the Pentax Papilio or Opticron Taiga would be great binos for kids except for one MAJOR failing--they don't have a small enough minimum interpupillary setting for most kids. In other words, the two sides of the bino don't come close enough together for a kid to actually see through both barrels. Many kids get used to only looking through one side (sometimes to the point that they don't realize they are doing it), but I don't consider that a good thing.
Right now, with a very few (and expensive) exceptions, the only binos with proper IPD spec for most 6 year olds are some traditional porro designs and the double-hinged pocket roof prism binoculars. The advantage of the former is that they have nice big exit pupils and they can have excellent optics at a low price, so they are easy to look through. The advantages of the latter are that they often focus closer (kids often like to look at nearby insects etc), fit kids' hands better (easier to reach the focus control), and are smaller overall.
My kids are now 4 and 7 years old. My 7 year old wears glasses. Both prefer the handling of the double-hinged pocket roofs over the porro, but when they want to see something, optical quality is more important to them than handling. Consequently, my son's favorite is my Zeiss 8x32 FL (expensive roof with 52 mm minimum IPD), followed by Leica 8x20 Ultravid (pocket roof), but if forced to pick between the Leupold 6x30 Yosemite (porro) and a cheap, optically crummy pocket roof like the Nikon 8x25 Sportstar, he much prefers the Yosemite. My 4 year old also prefers the view of the Yosemite but has a harder time w/the focus.
My recommendation is to first measure the IPD of your grandson. If he has an IPD of 56 mm or greater (unusual, but not impossible at this age) then you have the choice of most current and past production binoculars, in which case a moderately priced 8x32 roof with 6 foot close focus would be a good starting place (for combo of kid friendly ergonomics, decent optics, and close focus). If his IPD is under 56 mm, and you aren't wanting to spend lots of money, I'd pick the Leupold 6x30 Yosemite (minimum IPD is 50 mm) or a used vintage 8x30 porro with similar minimum IPD (must measure this before buying). If his IPD is much under 50 mm, the only good option is a pocket roof with the best optics you are willing to pay for.
In case my above comments aren't explicit enough, I'd say the Leupold 6x30 is the way to go unless his eyes or your wallet dimensions are outside the norm.
--AP
