Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 217 · 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.🛟 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
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) putting the iron away (d) dipping the cotton bud
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a small bowl (d) a balloon
5. 5.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a balloon (d) yeast
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
7. 7.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
9. 9.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
10. 10.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
11. 11.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a small bowl (d) yeast
14. 14.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) reading the message
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a mirror (d) a cotton bud
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the ironing time (d) the iron setting
19. 19.True or false: plugging in the iron is a job a child can do. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a magnet (d) a mirror
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a cotton bud (d) a balloon
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) a cotton bud (d) an adult with an iron
25. 25.True or false: cutting the lemon is a job a child can do. (a) False (b) True
26. 26.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
28. 28.True or false: reading the message is a job a child can do. (a) True (b) False
29. 29.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) letting the paper dry
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
32. 32.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
33. 33.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
34. 34.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) white paper
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
38. 38.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False

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