Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 975 · 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.🛟 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
2. 2.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
3. 3.🔮 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
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a balloon (d) white paper
5. 5.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
9. 9.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
10. 10.True or false: cutting the lemon is a job for an adult. (a) True (b) False
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
12. 12.⚖️ 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) False (b) True
13. 13.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) reading the message (d) dipping the cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
15. 15.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) reading the message
16. 16.⚖️ 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 keep it the same (c) we measure it
17. 17.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) white paper (d) a cotton bud
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a mirror (d) lemon juice
21. 21.⚖️ 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) True (b) False
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) white paper (d) a mirror
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a small bowl (d) a magnet
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
27. 27.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
28. 28.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the ironing time (d) the kind of juice
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) lemon juice (d) a battery cell
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a cotton bud (d) white paper
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a mirror (d) a cotton bud
35. 35.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
36. 36.🍋 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) writing the message
37. 37.🛟 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
38. 38.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
39. 39.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed

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