Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 436 · 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.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a mirror (d) a battery cell
2. 2.⚖️ 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 ironing time (c) the kind of juice (d) the iron setting
3. 3.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
4. 4.⚖️ 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
5. 5.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
6. 6.⚖️ 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
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
9. 9.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
12. 12.True or false: letting the paper dry is a job a child can do. (a) True (b) False
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
16. 16.True or false: plugging in the iron is a job a child can do. (a) False (b) True
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
18. 18.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) plugging in the iron (d) reading the message
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) white paper (d) turmeric powder
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) white paper
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
22. 22.⚖️ 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
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
26. 26.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) a small bowl (d) lemon juice
32. 32.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
33. 33.True or false: reading the message is a job for an adult. (a) True (b) False
34. 34.⚖️ 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
35. 35.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
36. 36.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
37. 37.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) reading the message (d) writing the message
39. 39.True or false: ironing the paper is a job a child can do. (a) False (b) True
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a mirror (d) a battery cell

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