Many of these resources are actually useful at a wide range of levels. Some would be useful from age 10 and upwards, depending on how the material surrounding the resource is presented. We list only a target level at which the resources in its presented form works well. Many teachers will find the resources useful in a wide range of circumstances.
Most High school students in New Zealand study for the National Certificate of Educational Achievement (NCEA). Study of material at NCEA level 1 is typically undertaken at age 15-16, level 2 at age 16-17, and level 3 at age 17-18.
For more information about Physics and the Physical World strand of the New Zealand Curriculum see NZC Online. For information about the  National Certificate of Educational Achievement (NCEA) consult the Physics subject resources pages produced by the New Zealand Qualifications Authority (NZQA). Physics is also assessed within Science subject resources at NCEA level 1.