Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 941 · 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 steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) cutting the lemon (d) putting the iron away
2. 2.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
4. 4.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) putting the iron away
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
6. 6.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
7. 7.🧺 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) a cotton bud
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) ironing the paper
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
10. 10.True or false: putting the iron away is a job for an adult. (a) True (b) False
11. 11.True or false: reading the message is a job a child can do. (a) True (b) False
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a balloon (d) a small bowl
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
14. 14.🛟 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
15. 15.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
16. 16.⚖️ 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 ironing time (d) the iron setting
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 ironing time (b) the iron setting (c) the kind of juice (d) how dark the writing is
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a cotton bud (d) yeast
20. 20.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) ironing the paper (d) plugging in the iron
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
22. 22.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
23. 23.⚖️ 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
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a small bowl (d) a battery cell
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
27. 27.True or false: ironing the paper is a job a child can do. (a) False (b) True
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
29. 29.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
30. 30.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
31. 31.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
32. 32.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
33. 33.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
34. 34.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
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 is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a battery cell (d) a magnet
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
38. 38.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) a small bowl
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False

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