7Pennsylvania Department of Education. Pennsylvania Learning Standards for Early Childhood [ EB/OL]. http://www, pakeys, org/pages/get, aspx? page career standards, pdf,2014-12-30.
8Michigan Department of Education. Science grade level content expectations [EB/OL]. http ://www. michigan. gov/mde/, pdf, 2009-01-27.
9Achieve, Inc. APPENDIXF - Science and Engineering Practices in the NGSS [EB/OL. http://www. nextgenscience, org/sites/ngss/files/Appendix/o 20F%20%20Science20and20Engineering%20PracticesX20in%20the%20NGSS%20-%20FINAL%20060513.pdf,2014—06—12.
10Proposed California's Next Generation Science Standards (NGSS) for K-12 Grade Kindergarten. California Department of Education,Rev. 2013-06-14.
