You might have received gift cards or cash as a gift for the holiday. Remember that you can buy my lab book "Chemistry on a Budget" for $20.54 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Another way to assess the quality of your lab results is to calculate the

**Percent Error**of the result. The formula for Percent Error is:

Percent error =

__measured value – accepted value__x 100% accepted value

Reminder, the % button is

*not*used on the calculator for this problem.

I did not include the absolute value brackets – some sources don’t include it – but I was taught to use it so it’s sort of hard to ignore it.

Here is a brief video (7 minutes) about this topic:

This narrator points out the use of absolute value brackets, and breaks down the formula to aid comprehension.

Here are a few worksheets to practice percent error calculations:

This page has mathematical questions with answers and also asks a few questions about accuracy and precision.

__http://www.sfponline.org/Uploads/382/acc_pres_percent_error_half-sheet.pdf__

For this worksheet, notice the directions at the top of the page require that work and units be shown.

__http://www.polk.k12.ga.us/userfiles/646/Classes/4526/Percent%20Error%20Practice%202.pdf__

This worksheet saves paper because it has the worksheet on the two halves of the page, and it has answers. (I hope you can find the paper cutter in your department!)

__http://mrnorton.com/assignment_calendar/PercentErrorPractice.pdf__

Check out the

**to help you to find past Blog entries. I hope it helps!**

*Topic List*Enjoy the rest of the holiday! I plan to discuss Midterm Examinations next week – I did post about Final Examinations on 06/08/2014. It may help!

Have a good New Year celebration!