## 08 Jan Washer and Candy Lab

Washer and Candy lab

Can you guess the number of each?

Teacher Notes

Materials Needed: Bags or cups, enough for 1 per group of students.  Two objects such as nuts, bolts, washers, candy, etc or 16d and 8d nails (they need to be uniform size), etc.  A scale that weighs in grams.

Procedure:

1. The teacher will weigh one washer and one candy in grams (if needed do more than one and find an average).Give this information to the students.
2. Have each group place a random number of washer and candy in a cup.They need to secretly record the number of each, as well as the total number of objects in the bag/cup.  Record the total number of objects on the bag/cup.
3. Each pair of groups will exchange cups.The receiving group can only weigh their new cup.  They cannot count them.  If you prefer, as teacher you can have cups/bags already prepared instead of the groups doing it.  This saves class time.
4. You can use a system of equations to solve.Your mathematical solution may not result in whole numberssince there may be a slight variance in manufacturing of nuts and bolts.  You will need to adjust.
5. Give a prize to those groups that can determine the number of nuts and number of bolts in their cup.

Sample:

washer (n)

candy (b)

washer weigh 20 grams

candy weigh 45 grams

Total weigh of cup of items 1990 grams

There are 72 objects in the cup

n + b = 72

20n + 45b = 1990