Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 551 · 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.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) yeast (d) lemon juice
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a small bowl (d) a cotton bud
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
6. 6.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
7. 7.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
8. 8.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
9. 9.⚖️ 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) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
11. 11.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
14. 14.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
15. 15.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) reading the message (d) dipping the cotton bud
16. 16.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
17. 17.True or false: writing the message is a job for an adult. (a) True (b) False
18. 18.⚖️ 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
19. 19.⚖️ 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 iron setting (c) the kind of juice
20. 20.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) plugging in the iron
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
22. 22.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) cutting the lemon (d) ironing the paper
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a cotton bud (d) a mirror
26. 26.True or false: plugging in the iron is a job for an adult. (a) True (b) False
27. 27.True or false: putting the iron away is a job for an adult. (a) True (b) False
28. 28.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a mirror (d) lemon juice
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a battery cell
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
32. 32.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the kind of juice (d) the iron setting
35. 35.True or false: reading the message is a job a child can do. (a) True (b) False
36. 36.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
37. 37.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) cutting the lemon
38. 38.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) turmeric powder (d) lemon juice
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed

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