### Where Can We Visit?

Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: x2 and -5. What do you think?

### Arithmagons

Can you find the values at the vertices when you know the values on the edges?

### Babylon Numbers

Can you make a hypothesis to explain these ancient numbers?

# Reaction Timer

##### Age 11 to 14Challenge Level

We received a number of observations and conjectures.

Octavia from Fowlmere suggested the following

• Right handers are better at reacting with their right hand and left handers vice versa
• At night you are more tired so your reactions are slower
• Males tend to be quicker than females because they play more computer and playstation games
• The older you are the more time it takes for you to react because your body doesn't work as fast

Meghan from AHS suggested that if you change the properties of the star, it is harder to click it quickly. She also added that males are actually no quicker than females. We already have conflicting conjectures, and this is where providing real data in support of your argument is important.

Maria and Katie from St Mary's conducted an experiment, in which they found that the average reaction time for their left hand was 0.2s, while for their right hand it was 0.15s. Rosie, Natalie and Gabby, also from St Mary's provided similar data which supports the argument that we react quicker with our better hand.

Michael from Lancaster Grammar experimented with a moving star. He made the following acute remark: "If you are right handed have the mouse at the right side of the screen, so when a star does come it is easier to get to the star because your right hand can move faster and more easily to the star if it is at the left."

This raises an important issue - that factors other than reaction time (such as strategy) can affect our results. In conducting a fair experiment it is essential to make sure that these other factors are controlled.

Some students from Hampton School suggested some other factors that may affect reaction time:

Your reactions are always faster if you limit the number of things you have to be aware of - Harry
People with better eyesight have quicker reaction time - Matt
The time you get varies depending on whether you pay close attention or not - Nick

In response to our demand for experimental data, a number of students from Chalkstone Middle School sent in their findings. Sithabile and Shannon sent in some data and concluded that we react fastest with our best hand. Kelly, however, claimed that people always do better with their left hand. Keeley claimed that boys have better reactions than girls while under stress, but otherwise girls are quicker!

The data were well organised and clearly presened, but in many cases we were concerned that there were not enough data to truly back up your claims. A number of you based your conclusions on testing each individual in your sample just once. Aaron and Eshter made an effort to get more accurate results by repeating individual experiments three times.