It didn't take Alex long to size up the situation.
As regards the dentition of the existing species, the cheek-series consists of the four premolars and three molars above and below, all in contact and closely resembling each other, except the first, which is much smaller than the rest and often deciduous; the others gradually increasing in size up to the penultimate.
One size up should be sufficient to provide your child with room to grow.
You need to know the length and width of your table so you can size up cloths/runners.
If your window appears to be slightly between sizes, size up to the larger; over extending a telescoping rod may cause it to bend in the center.