Describe how you would help your learners in a primary class to multiply the following using number line: 7 x 1/3, 10 x 2/5, 2 x 4/5, 3 x 1/3, 4 x 2/4.

Mark intervals of $\frac{1}{3}$.

$$7 \times \frac{1}{3}$$

Make 7 jumps of $\frac{1}{3}$ each.

After 1 jump: $0 + \frac{1}{3} = \frac{1}{3}$

After 2 jumps: $\frac{1}{3} + \frac{1}{3} = \frac{2}{3}$

After 3 jumps: $\frac{2}{3} + \frac{1}{3} = \frac{3}{3} = 1$

After 4 jumps: $1 + \frac{1}{3} = \frac{4}{3}$

After 5 jumps: $\frac{4}{3} + \frac{1}{3} = \frac{5}{3}$

After 6 jumps: $\frac{5}{3} + \frac{1}{3} = \frac{6}{3} = 2$

After 7 jumps: $2 + \frac{1}{3} = \frac{7}{3}$

Final answer: $\boxed{\dfrac{7}{3}}$

B. $3 \times \frac{1}{5}$

Mark intervals of $\frac{1}{5}$.

$$3 \times \frac{1}{5}$$

Make 3 jumps of $\frac{1}{5}$ each.

After 1 jump: $0 + \frac{1}{5} = \frac{1}{5}$

After 2 jumps: $\frac{1}{5} + \frac{1}{5} = \frac{2}{5}$

After 3 jumps: $\frac{2}{5} + \frac{1}{5} = \frac{3}{5}$

Final answer: $\boxed{\dfrac{3}{5}}$

C. $2 \times \frac{1}{10}$

Mark intervals of $\frac{1}{10}$.

$$2 \times \frac{1}{10}$$

Make 2 jumps of $\frac{1}{10}$ each.

After 1 jump: $0 + \frac{1}{10} = \frac{1}{10}$

After 2 jumps: $\frac{1}{10} + \frac{1}{10} = \frac{2}{10} = \frac{1}{5}$

Final answer: $\boxed{\dfrac{1}{5}}$

D. $4 \times \frac{1}{2}$

Mark intervals of $\frac{1}{2}$.

$$4 \times \frac{1}{2}$$

Make 4 jumps of $\frac{1}{2}$ each.

After 1 jump: $0 + \frac{1}{2} = \frac{1}{2}$

After 2 jumps: $\frac{1}{2} + \frac{1}{2} = \frac{2}{2} = 1$

After 3 jumps: $1 + \frac{1}{2} = \frac{3}{2}$

After 4 jumps: $\frac{3}{2} + \frac{1}{2} = \frac{4}{2} = 2$

Final answer: $\boxed{2}$