Kids love to measure, especially 2nd graders. They’ll measure anything they can get their hands on, and it behooves us to give them plenty to measure so they can develop these motor, perceptual, and spatial skills while they’re still interested.
Here are some collections I have put together for measurement activities using both inches and centimeters. These measurements are then the basis for plenty of questions and problems to solve: “What was the longest item in the bag?…the shortest?…How much longer was the spoon than the paper clip?…”
Also, here’s a list of common classroom or household objects that have more-or-less standard dimensions. These make collecting similar sets of objects go a little faster. The dimensions are not exactly to the inch or centimeter, but they’re visibly closer to one than the other, so the focus stays on measuring accurately and not rounding. You can always find colored posterboard or cardstock to cut, of course.
Please add to this list!
If you begin to collect things, remember that 5 cm = 2 inches, and 10 cm = 4 inches. This makes it go a little easier.
Here are some pretty standard dimensions for common objects. Where one measurement is left out, the true measurement is too close to half to bother with, IMO. Again, the focus is on accurate measurement, not rounding.
Units Inches CM
#2 paper clip 2″ 10 cm
Spaghetti (before it breaks) 9″ 23 cm
A pattern block trapezoid (long edge) 2″ 10 cm
Sharpie marker (and many other markers/pens) 14 cm
Extremely small paper clip 1″
Common Band Aid (in wrapper) 4″ 10 cm
Plastic spoon 6″ 15 cm
Long drinking straw 8″
Standard business envelope (length) 24 cm
New pencil 19 cm
New crayon 9 cm
A Ten Rod 4″ 10 cm
Index card 3 by 5 5″ long
Index card 4 by 6 4″ wide 10 cm
Index card 4 by 6 6″ long 15 cm
Hardware: You can buy screws, bolts, and nails to length. I have nails (which I grind the points of) and you can buy cheap machine screws in lengths of up to 3” or so. Machine bolts can be found in longer sizes, but are more expensive.