# 4.5: Critter Trades

**At Grade**Created by: CK-12

Look at the picture below. Can you figure out how many moths you could get for 4 centipedes? In this concept, we will learn about trading and calculating the result of a trade.

### Guidance

In order to solve the trading problem above, use the problem solving steps.

- Start by
**describing**what information is given. - Then, identify what
**your job**is. In these problems, your job will be to figure out how many of another type of critter you could get for the critters you have. - Next, make a
**plan**for how you will solve. In these problems, write numbers on each of your critters and skip count to figure out how many of the new critter you will get. - Then,
**solve**the problem. - Finally,
**check**your solution. Make sure that you added the numbers correctly.

#### Example A

Look at the picture below. For 3 spiders, how many bees will you get? How did you figure it out?

**Solution:**

We can use the problem solving steps to help us.

\begin{align*}& \mathbf{Describe:} && \text{There are two different critters.}\\ &&& \text{For 1 spider I get 2 bees.}\\ & \mathbf{My \ Job:} && \text{Figure out how many bees I get for 3 spiders.}\\ & \mathbf{Plan:} && \text{Write 2 on each of the 3 spiders.}\\ &&& \text{Then skip count the 2s.}\\ & \mathbf{Solve:} \end{align*}

\begin{align*}& \mathbf{Check:} && 2 + 2 + 2 =6\end{align*}

#### Example B

Look at the picture below. For 4 grasshoppers, how many butterflies will you get? How did you figure it out?

**Solution:**

We can use the problem solving steps to help us.

\begin{align*}& \mathbf{Describe:} && \text{There are two different critters.}\\ &&& \text{For 1 grasshopper I get 3 butterflies.}\\ & \mathbf{My \ Job:} && \text{Figure out how many butterflies I get for 4 grasshoppers.}\\ & \mathbf{Plan:} && \text{Write 3 on each of the 4 grasshoppers.}\\ &&& \text{Then skip count the 3s.}\\ & \mathbf{Solve:} \end{align*}

\begin{align*}& \mathbf{Check:} && 3 + 3 + 3 + 3 =12\end{align*}

#### Example C

Look at the picture below. For 5 flies, how many ants will you get? How did you figure it out?

**Solution:**

We can use the problem solving steps to help us.

\begin{align*}& \mathbf{Describe:} && \text{There are two different critters.}\\ &&& \text{For 1 fly I get 3 ants.}\\ & \mathbf{My \ Job:} && \text{Figure out how many ants I get for 5 flies.}\\ & \mathbf{Plan:} && \text{Write 3 on each of the 5 flies.}\\ &&& \text{Then skip count the 3s.}\\ & \mathbf{Solve:} \end{align*}

\begin{align*}& \mathbf{Check:} && 3 + 3 + 3 + 3 +3= 15\end{align*}

#### Concept Problem Revisited

We can use the problem solving steps to help us.

\begin{align*}& \mathbf{Describe:} && \text{There are two different critters.}\\ &&& \text{For 1 centipede I get 3 moths.}\\ & \mathbf{My \ Job:} && \text{Figure out how many moths I can get for 4 centipedes.}\\ & \mathbf{Plan:} && \text{Write 3 on each of the 4 centipedes.}\\ &&& \text{Then skip count the 3s.}\\ & \mathbf{Solve:} \end{align*}

\begin{align*}& \mathbf{Check:} && 3 + 3 + 3 + 3 = 12\end{align*}

### Vocabulary

To ** trade** means you give something and get something else back. In this concept, we calculated what we would get if we

**critters.**

*traded*### Guided Practice

1. For 10 scorpions, how many wasps will you get?

2. To get 6 worms, how many daddy long legs will you need to trade?

3. To get 24 ants, how many lizards will you need to trade?

**Answers:**

1. 40

2. 3

3. 4

### Practice

- For 10 daddy long legs, how many worms will you get?
- To get 12 worms, how many daddy long legs will you need to trade?
- To get 18 worms, how many daddy long legs will you need to trade?

- For 8 flies, how many ants will you get?
- To get 35 ants, how many flies will you need to trade?
- To get 45 ants, how many flies will you need to trade?

- For 6 grasshoppers, how many wasps will you get?
- To get 42 wasps, how many grasshoppers will you need to trade?
- To get 24 wasps, how many grasshoppers will you need to trade?

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### Image Attributions

Students reason proportionally as they trade critters. Students use problem solving steps to help them.