Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 174 · 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.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a mirror (d) an adult with an iron
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) lemon juice (d) white paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) lemon juice (d) a magnet
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
8. 8.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) yeast
10. 10.True or false: cutting the lemon is a job for an adult. (a) False (b) True
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a battery cell (d) a magnet
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
13. 13.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a mirror (d) a cotton bud
15. 15.⚖️ 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
16. 16.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
17. 17.True or false: ironing the paper is a job for an adult. (a) False (b) True
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
19. 19.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the same paper (d) the same cotton bud
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a battery cell (d) a small bowl
22. 22.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a small bowl (d) white paper
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) ironing the paper
25. 25.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: ironing the paper is a job a child can do. (a) True (b) False
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
28. 28.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) a balloon (d) lemon juice
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
31. 31.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
32. 32.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
33. 33.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
34. 34.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
36. 36.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the kind of juice
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) writing the message (d) letting the paper dry
40. 40.⚖️ 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 keep it the same (c) we change it

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