Egyptian knotted string Use plain kite string and bring geometry into your math program. The ancient Egyptians used string. They knotted it and stretched it to do their measuring. A very young child can get the idea of making geometric measurements the same way.
Children can begin to comprehend the rudiments of geometry with string by being measured themselves.
In kindergarten and first and second grade, a teacher can take children's measurements and use their respective heights as basic length-units for having them measure things in the immediate environs. That's what the Egyptians did. A string with knots carefully made at both ends becomes your basic line segment. Measuring is matching. I am this big.