use a ruler to measure to the nearest centimeter and 1/4 inch;
http://www.funbrain.com/measure/index.html
http://www.bgfl.org/bgfl/custom/resources_ftp/client_ftp/ks2/maths/measures/index.htm
http://www.studyzone.org/mtestprep/math8/k/metricp.cfm
http://www.apples4theteacher.com/measure.html
http://library.thinkquest.org/3804/length.html