Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 481 · 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 an adult with an iron for the secret lemon message? (a) not needed (b) needed
2. 2.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
3. 3.⚖️ 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) False (b) True
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) an adult with an iron (d) a small bowl
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a magnet (d) a battery cell
9. 9.⚖️ 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 ironing time (c) the kind of juice
10. 10.🛟 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
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) an adult with an iron (d) a cotton bud
12. 12.True or false: plugging in the iron is a job for an adult. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
16. 16.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) writing the message
17. 17.⚖️ 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 same cotton bud (c) the kind of juice (d) how dark the writing is
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
19. 19.True or false: putting the iron away is a job a child can do. (a) True (b) False
20. 20.True or false: putting the iron away is a job for an adult. (a) False (b) True
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) lemon juice (d) a magnet
22. 22.⚖️ 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) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
24. 24.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
25. 25.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 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) a small bowl (d) a balloon
27. 27.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) an adult with an iron (d) a magnet
29. 29.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a mirror (d) white paper
31. 31.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
32. 32.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) letting the paper dry
33. 33.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
35. 35.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) putting the iron away
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
37. 37.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) reading the message
39. 39.True or false: writing the message is a job for an adult. (a) False (b) True
40. 40.True or false: white paper is not needed for the secret lemon message. (a) True (b) False

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