Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 186 · 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.🧺 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
2. 2.⚖️ 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) False (b) True
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) white paper (d) yeast
4. 4.🧺 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 cotton bud (d) a battery cell
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
6. 6.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
7. 7.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
9. 9.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) reading the message
10. 10.True or false: plugging in the iron is a job a child can do. (a) False (b) True
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) turmeric powder (d) white paper
12. 12.⚖️ 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
13. 13.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
14. 14.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) an adult with an iron (d) a magnet
16. 16.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same cotton bud (c) the same paper (d) the ironing time
18. 18.True or false: reading the message is a job a child can do. (a) True (b) False
19. 19.⚖️ 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
20. 20.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
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 keep it the same (b) we change it (c) we measure it
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, if shaken (d) yes, in the dark
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ 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
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) white paper (d) an adult with an iron
30. 30.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
31. 31.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) lemon juice
33. 33.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
34. 34.🛟 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
35. 35.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) yeast (d) a small bowl
37. 37.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) ironing the paper (d) plugging in the iron
38. 38.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
39. 39.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
40. 40.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper

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