Three Children Grow Two Inches Overnight

Here's the door from the kitchen to the back porch. We've always measured our three childrens' heights using the chart we pin to the back of the door. Yesterday we found the two youngest had grown two inches each since September when they were last measured. Wow! We became suspicious when the eldest was measured today and was also found to have grown by over two inches. Then it clicked. I sawed two inches off the bottom of the door a few weeks ago to accommodate the rise in floor level in the porch caused by the pouring of a load of concrete in the bathroom and porch for ther installation of the wet room. After moving the pin down the children have been measured again. They have not had a sudden unexpected growth spurt.