Year 9 Investigation: Levels 6-7
JELLY SNAKES
Jelly snakes are found everywhere from cupboards to lolly shops. The brave Math teachers of Cranbourne East Secondary College have courageously caught several different species of Jelly snakes of varying lengths. Your job is to study the properties of the snakes, focusing especially on how they stretch. You will need to write a report about how stretchy each species of snake is along with a graph of how far they stretched for each set of weights.
WHAT DO YOU NEED…?
You will need masking tape, 2 large paperclips, retort stand, clamp, boss, 50g weights and carrier, tape measure or ruler and especially 4 different species of jelly snakes!
JELLY SNAKES
Before you start testing the snakes you need to prepare. To do this follow the four steps below:
1. Wrap a ring of masking tape tightly around each end of the snake.
2. Push a large paperclip through the masking tape at each end of the snake.
3. Secure the snake to the retort stand.
4. Attach a measuring tape to the top paperclip.
TESTING THE SNAKES
Use the following steps to test the stretchiness of each species of snake.
1. Measure the initial length of the snake in millimetres (mm). Record this length in the table below.
2. Attach the 50g weight to the paper clip at the bottom of the snake. Allow a few 3moments for the snake to stretch and then measure its new length. Put the new length in the table.
3. Add another 50g weight and measure the length of the snake again.
4. Continue adding 50g weights and measuring the length of the snake
until it breaks.
5. Repeat step 1 to 4 with the other 3 species of snakes.
RESULTS
Use this table to record the results of the stretching of the snakes.
Weight (g) / Snake A Brand: / Snake B Brand: / Snake C Brand: / Snake D Brand:Length (mm) / Length (mm) / Length (mm) / Length (mm)
0
50
100
150
200
250
300
350
400
450
500
WRITING YOUR REPORT
Use the level ladder to determine what needs to be included in your report. For example, with level 7 you need to include a graph that shows how far each snake stretches. Use the values that you have put into your table for this. You will also need to come up with an expression about the length of the snake to the weight hanging off it.
6 / · Recorded your results accurately into the table.
· Used diagrams and tables to help solve the problem
· Determined a rule for the length that each snake stretches for a given weight.
· Plot the data points onto a graph.
7 / · Recorded your results accurately into the table.
· Using data tables produce a graph. From the graph come up with a relation between the length that each snake stretches for a given weight.
· Found the gradient and y-intercept for each species of snake.
· Commented on any patterns discovered while solving the problem
8 / · Used graphs or other methods to determine a linear equation
· Calculated the length that each species of snake would stretch for 80, 120 and 330 grams.
· Discussed and explained any patterns discovered while solving the problem.
9 / · Used graphs or other methods to determine linear equations for each shape.
· Calculated the length that each species of snake would stretch for 80, 120 and 330 grams.
· Calculated the weight needed that stretches each of the species to 22, 30 and 35mm.
· Discussed and explained why the rule works for the different species of snakes and why each snake species has a different rule.