Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 915 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) the kind of juice (d) the same cotton bud
3. 3.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) letting the paper dry
9. 9.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) cutting the lemon
10. 10.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) putting the iron away (d) plugging in the iron
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
12. 12.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) writing the message (d) reading the message
14. 14.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
15. 15.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) lemon juice (d) a mirror
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a magnet (d) white paper
18. 18.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
19. 19.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
20. 20.True or false: writing the message is a job a child can do. (a) False (b) True
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is magnetic (d) it is cold
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) turmeric powder (d) lemon juice
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a battery cell (c) an adult with an iron (d) lemon juice
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a magnet
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
27. 27.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
28. 28.True or false: letting the paper dry is a job for an adult. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
30. 30.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) ironing the paper
34. 34.True or false: cutting the lemon is a job a child can do. (a) True (b) False
35. 35.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
37. 37.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
38. 38.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) turmeric powder (d) white paper
40. 40.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) putting the iron away (c) ironing the paper (d) plugging in the iron

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